diff --git a/server/src/api/controllers/ExchangeRates.ts b/server/src/api/controllers/ExchangeRates.ts
index dd523ce7b..e1bf38503 100644
--- a/server/src/api/controllers/ExchangeRates.ts
+++ b/server/src/api/controllers/ExchangeRates.ts
@@ -103,7 +103,7 @@ export default class ExchangeRatesController extends BaseController {
     const { tenantId } = req;
     const filter = {
       page: 1,
-      pageSize: 100,
+      pageSize: 12,
       filterRoles: [],
       columnSortBy: 'created_at',
       sortOrder: 'asc',
diff --git a/server/src/api/controllers/Purchases/Bills.ts b/server/src/api/controllers/Purchases/Bills.ts
index ad8d75c07..9d9684d38 100644
--- a/server/src/api/controllers/Purchases/Bills.ts
+++ b/server/src/api/controllers/Purchases/Bills.ts
@@ -48,7 +48,7 @@ export default class BillsController extends BaseController {
     );
     router.post(
       '/:id', [
-        ...this.billValidationSchema,
+        ...this.billEditValidationSchema,
         ...this.specificBillValidationSchema,
       ],
       this.validationResult,
@@ -106,7 +106,6 @@ export default class BillsController extends BaseController {
 
       check('entries').isArray({ min: 1 }),
 
-      check('entries.*.id').optional().isNumeric().toInt(),
       check('entries.*.index').exists().isNumeric().toInt(),
       check('entries.*.item_id').exists().isNumeric().toInt(),
       check('entries.*.rate').exists().isNumeric().toFloat(),
@@ -121,7 +120,7 @@ export default class BillsController extends BaseController {
    */
   get billEditValidationSchema() {
     return [
-      check('bill_number').exists().trim().escape(),
+      check('bill_number').optional().trim().escape(),
       check('reference_no').optional().trim().escape(),
       check('bill_date').exists().isISO8601(),
       check('due_date').optional().isISO8601(),
diff --git a/server/src/api/controllers/Purchases/BillsPayments.ts b/server/src/api/controllers/Purchases/BillsPayments.ts
index f26635db8..297472803 100644
--- a/server/src/api/controllers/Purchases/BillsPayments.ts
+++ b/server/src/api/controllers/Purchases/BillsPayments.ts
@@ -407,6 +407,11 @@ export default class BillsPayments extends BaseController {
           errors: [{ type: 'BILLS_NOT_FOUND', code: 1000 }],
         });
       }
+      if (error.errorType === 'PAYMENT_NUMBER_SHOULD_NOT_MODIFY') {
+        return res.status(400).send({
+          errors: [{ type: 'PAYMENT_NUMBER_SHOULD_NOT_MODIFY', code: 1100 }],
+        });
+      }
     }
     next(error);
   }
diff --git a/server/src/api/controllers/Sales/PaymentReceives.ts b/server/src/api/controllers/Sales/PaymentReceives.ts
index 271607148..70d521885 100644
--- a/server/src/api/controllers/Sales/PaymentReceives.ts
+++ b/server/src/api/controllers/Sales/PaymentReceives.ts
@@ -91,6 +91,7 @@ export default class PaymentReceivesController extends BaseController {
    */
   get paymentReceiveSchema(): ValidationChain[] {
     return [
+      check('customer_id').exists().isNumeric().toInt(),
       check('payment_date').exists(),
       check('reference_no').optional(),
       check('deposit_account_id').exists().isNumeric().toInt(),
@@ -132,7 +133,6 @@ export default class PaymentReceivesController extends BaseController {
    */
   get newPaymentReceiveValidation() {
     return [
-      check('customer_id').exists().isNumeric().toInt(),
       ...this.paymentReceiveSchema,
     ];
   }
@@ -449,6 +449,11 @@ export default class PaymentReceivesController extends BaseController {
           errors: [{ type: 'PAYMENT_RECEIVE_NO_IS_REQUIRED', code: 1100 }],
         });
       }
+      if (error.errorType === 'PAYMENT_CUSTOMER_SHOULD_NOT_UPDATE') {
+        return res.boom.badRequest(null, {
+          errors: [{ type: 'PAYMENT_CUSTOMER_SHOULD_NOT_UPDATE', code: 1200 }],
+        });
+      }
     }
     next(error);
   }
diff --git a/server/src/api/controllers/Sales/SalesInvoices.ts b/server/src/api/controllers/Sales/SalesInvoices.ts
index 81c09eadd..2e104def2 100644
--- a/server/src/api/controllers/Sales/SalesInvoices.ts
+++ b/server/src/api/controllers/Sales/SalesInvoices.ts
@@ -301,6 +301,7 @@ export default class SaleInvoicesController extends BaseController {
         filterMeta,
         pagination,
       } = await this.saleInvoiceService.salesInvoicesList(tenantId, filter);
+
       return res.status(200).send({
         sales_invoices: salesInvoices,
         pagination: this.transfromToResponse(pagination),
diff --git a/server/src/database/migrations/20200713192127_create_sales_estimates_table.js b/server/src/database/migrations/20200713192127_create_sales_estimates_table.js
index 18e8377b4..6bd95c289 100644
--- a/server/src/database/migrations/20200713192127_create_sales_estimates_table.js
+++ b/server/src/database/migrations/20200713192127_create_sales_estimates_table.js
@@ -4,6 +4,7 @@ exports.up = function(knex) {
   return knex.schema.createTable('sales_estimates', (table) => {
     table.increments();
     table.decimal('amount', 13, 3);
+    table.string('currency_code', 3);
     table.integer('customer_id').unsigned().index().references('id').inTable('contacts');
     table.date('estimate_date').index();
     table.date('expiration_date').index();
diff --git a/server/src/database/migrations/20200713213303_create_sales_receipt_table.js b/server/src/database/migrations/20200713213303_create_sales_receipt_table.js
index f07d52e4c..c1f093312 100644
--- a/server/src/database/migrations/20200713213303_create_sales_receipt_table.js
+++ b/server/src/database/migrations/20200713213303_create_sales_receipt_table.js
@@ -3,6 +3,7 @@ exports.up = function(knex) {
   return knex.schema.createTable('sales_receipts', table => {
     table.increments();
     table.decimal('amount', 13, 3);
+    table.string('currency_code', 3);
     table.integer('deposit_account_id').unsigned().index().references('id').inTable('accounts');
     table.integer('customer_id').unsigned().index().references('id').inTable('contacts');
     table.date('receipt_date').index();
diff --git a/server/src/database/migrations/20200715193633_create_sale_invoices_table.js b/server/src/database/migrations/20200715193633_create_sale_invoices_table.js
index 4629c4a3c..010a17c26 100644
--- a/server/src/database/migrations/20200715193633_create_sale_invoices_table.js
+++ b/server/src/database/migrations/20200715193633_create_sale_invoices_table.js
@@ -13,6 +13,7 @@ exports.up = function(knex) {
 
     table.decimal('balance', 13, 3);
     table.decimal('payment_amount', 13, 3);
+    table.string('currency_code', 3);
 
     table.string('inv_lot_number').index();
 
diff --git a/server/src/database/migrations/20200715194514_create_payment_receives_table.js b/server/src/database/migrations/20200715194514_create_payment_receives_table.js
index 7dc739e57..4c24aa1dc 100644
--- a/server/src/database/migrations/20200715194514_create_payment_receives_table.js
+++ b/server/src/database/migrations/20200715194514_create_payment_receives_table.js
@@ -6,6 +6,7 @@ exports.up = function(knex) {
     table.integer('customer_id').unsigned().index().references('id').inTable('contacts');
     table.date('payment_date').index();
     table.decimal('amount', 13, 3).defaultTo(0);
+    table.string('currency_code', 3);
     table.string('reference_no').index();
     table.integer('deposit_account_id').unsigned().references('id').inTable('accounts');
     table.string('payment_receive_no').nullable();
diff --git a/server/src/database/migrations/20200719152005_create_bills_table.js b/server/src/database/migrations/20200719152005_create_bills_table.js
index 8dc2ce1aa..c8c432a32 100644
--- a/server/src/database/migrations/20200719152005_create_bills_table.js
+++ b/server/src/database/migrations/20200719152005_create_bills_table.js
@@ -10,6 +10,7 @@ exports.up = function(knex) {
     table.string('status').index();
     table.text('note');
     table.decimal('amount', 13, 3).defaultTo(0);
+    table.string('currency_code');
     table.decimal('payment_amount', 13, 3).defaultTo(0);
     table.string('inv_lot_number').index();
     table.date('opened_at').index();
diff --git a/server/src/database/migrations/20200719153909_create_bills_payments_table.js b/server/src/database/migrations/20200719153909_create_bills_payments_table.js
index e61b93e5c..1e618b5dd 100644
--- a/server/src/database/migrations/20200719153909_create_bills_payments_table.js
+++ b/server/src/database/migrations/20200719153909_create_bills_payments_table.js
@@ -4,6 +4,7 @@ exports.up = function(knex) {
     table.increments();
     table.integer('vendor_id').unsigned().index().references('id').inTable('contacts');
     table.decimal('amount', 13, 3).defaultTo(0);
+    table.string('currency_code');
     table.integer('payment_account_id').unsigned().references('id').inTable('accounts');
     table.string('payment_number').nullable().index();
     table.date('payment_date').index();
diff --git a/server/src/interfaces/PaymentReceive.ts b/server/src/interfaces/PaymentReceive.ts
index a545b8a01..40dcb40ac 100644
--- a/server/src/interfaces/PaymentReceive.ts
+++ b/server/src/interfaces/PaymentReceive.ts
@@ -25,6 +25,7 @@ export interface IPaymentReceiveCreateDTO {
 };
 
 export interface IPaymentReceiveEditDTO {
+  customerId: number,
   paymentDate: Date,
   amount: number,
   referenceNo: string,
diff --git a/server/src/interfaces/SaleEstimate.ts b/server/src/interfaces/SaleEstimate.ts
index 8cc086e43..f3679570d 100644
--- a/server/src/interfaces/SaleEstimate.ts
+++ b/server/src/interfaces/SaleEstimate.ts
@@ -4,6 +4,7 @@ import { IDynamicListFilterDTO } from 'interfaces/DynamicFilter';
 export interface ISaleEstimate {
   id?: number,
   amount: number,
+  currencyCode: string,
   customerId: number,
   estimateDate: Date,
   estimateNumber: string,
diff --git a/server/src/interfaces/SaleInvoice.ts b/server/src/interfaces/SaleInvoice.ts
index ff0447109..d3789b011 100644
--- a/server/src/interfaces/SaleInvoice.ts
+++ b/server/src/interfaces/SaleInvoice.ts
@@ -5,6 +5,7 @@ export interface ISaleInvoice {
   id: number,
   balance: number,
   paymentAmount: number,
+  currencyCode: string,
   invoiceDate: Date,
   dueDate: Date,
   dueAmount: number,
diff --git a/server/src/interfaces/SaleReceipt.ts b/server/src/interfaces/SaleReceipt.ts
index 687441291..2046eddae 100644
--- a/server/src/interfaces/SaleReceipt.ts
+++ b/server/src/interfaces/SaleReceipt.ts
@@ -10,6 +10,7 @@ export interface ISaleReceipt {
   receiptMessage: string;
   receiptNumber: string;
   amount: number;
+  currencyCode: string,
   statement: string;
   closedAt: Date | string;
   entries: any[];
diff --git a/server/src/services/Contacts/ContactsService.ts b/server/src/services/Contacts/ContactsService.ts
index 938af5f46..92cf31ac7 100644
--- a/server/src/services/Contacts/ContactsService.ts
+++ b/server/src/services/Contacts/ContactsService.ts
@@ -63,6 +63,11 @@ export default class ContactsService {
    * @param {IContactNewDTO | IContactEditDTO} contactDTO
    */
   private transformContactObj(contactDTO: IContactNewDTO | IContactEditDTO) {
+    const baseCurrency = 'USD';
+    const currencyCode = typeof contactDTO.currencyCode !== 'undefined'
+    ? contactDTO.currencyCode
+    : baseCurrency;
+
     return {
       ...omit(contactDTO, [
         'billingAddress1',
@@ -74,6 +79,7 @@ export default class ContactsService {
       billing_address_2: contactDTO?.billingAddress2,
       shipping_address_1: contactDTO?.shippingAddress1,
       shipping_address_2: contactDTO?.shippingAddress2,
+      ...(currencyCode ? ({ currencyCode }) : {}),
     };
   }
 
@@ -99,7 +105,6 @@ export default class ContactsService {
       contactService,
       ...contactObj,
     });
-
     this.logger.info('[contacts] contact inserted successfully.', {
       tenantId,
       contact,
@@ -123,12 +128,12 @@ export default class ContactsService {
     const { contactRepository } = this.tenancy.repositories(tenantId);
     const contactObj = this.transformContactObj(contactDTO);
 
+    // Retrieve the given contact by id or throw not found service error.
     const contact = await this.getContactByIdOrThrowError(
       tenantId,
       contactId,
       contactService
     );
-
     this.logger.info('[contacts] trying to edit the given contact details.', {
       tenantId,
       contactId,
@@ -196,7 +201,7 @@ export default class ContactsService {
     const dynamicList = await this.dynamicListService.dynamicList(
       tenantId,
       Contact,
-      contactsFilter,
+      contactsFilter
     );
     // Retrieve contacts list by the given query.
     const contacts = await Contact.query().onBuild((builder) => {
diff --git a/server/src/services/Contacts/VendorsService.ts b/server/src/services/Contacts/VendorsService.ts
index 052505823..ada57f3d2 100644
--- a/server/src/services/Contacts/VendorsService.ts
+++ b/server/src/services/Contacts/VendorsService.ts
@@ -116,7 +116,7 @@ export default class VendorsService {
    * @param {number} tenantId
    * @param {number} customerId
    */
-  private getVendorByIdOrThrowError(tenantId: number, customerId: number) {
+  public getVendorByIdOrThrowError(tenantId: number, customerId: number) {
     return this.contactService.getContactByIdOrThrowError(
       tenantId,
       customerId,
diff --git a/server/src/services/Inventory/Inventory.ts b/server/src/services/Inventory/Inventory.ts
index 7d2312f79..5159abd8a 100644
--- a/server/src/services/Inventory/Inventory.ts
+++ b/server/src/services/Inventory/Inventory.ts
@@ -54,9 +54,9 @@ export default class InventoryService {
   /**
    * Computes the given item cost and records the inventory lots transactions
    * and journal entries based on the cost method FIFO, LIFO or average cost rate.
-   * @param {number} tenantId -
-   * @param {Date} fromDate -
-   * @param {number} itemId -
+   * @param {number} tenantId - Tenant id.
+   * @param {Date} fromDate - From date.
+   * @param {number} itemId - Item id.
    */
   async computeItemCost(tenantId: number, fromDate: Date, itemId: number) {
     const { Item } = this.tenancy.models(tenantId);
diff --git a/server/src/services/Purchases/BillPayments.ts b/server/src/services/Purchases/BillPayments.ts
index ce7bf769b..989a2427f 100644
--- a/server/src/services/Purchases/BillPayments.ts
+++ b/server/src/services/Purchases/BillPayments.ts
@@ -27,6 +27,7 @@ import DynamicListingService from 'services/DynamicListing/DynamicListService';
 import { entriesAmountDiff, formatDateFields } from 'utils';
 import { ServiceError } from 'exceptions';
 import { ACCOUNT_PARENT_TYPE } from 'data/AccountTypes';
+import VendorsService from 'services/Contacts/VendorsService';
 
 const ERRORS = {
   BILL_VENDOR_NOT_FOUND: 'VENDOR_NOT_FOUND',
@@ -38,6 +39,7 @@ const ERRORS = {
   BILL_ENTRIES_IDS_NOT_FOUND: 'BILL_ENTRIES_IDS_NOT_FOUND',
   BILL_PAYMENT_ENTRIES_NOT_FOUND: 'BILL_PAYMENT_ENTRIES_NOT_FOUND',
   INVALID_BILL_PAYMENT_AMOUNT: 'INVALID_BILL_PAYMENT_AMOUNT',
+  PAYMENT_NUMBER_SHOULD_NOT_MODIFY: 'PAYMENT_NUMBER_SHOULD_NOT_MODIFY',
 };
 
 /**
@@ -58,6 +60,9 @@ export default class BillPaymentsService {
   @Inject()
   dynamicListService: DynamicListingService;
 
+  @Inject()
+  vendorsService: VendorsService;
+
   @EventDispatcher()
   eventDispatcher: EventDispatcherInterface;
 
@@ -118,7 +123,6 @@ export default class BillPaymentsService {
     const paymentAccount = await accountRepository.findOneById(
       paymentAccountId
     );
-
     if (!paymentAccount) {
       throw new ServiceError(ERRORS.PAYMENT_ACCOUNT_NOT_FOUND);
     }
@@ -263,6 +267,45 @@ export default class BillPaymentsService {
     }
   }
 
+  /**
+   * * Validate the payment vendor whether modified.
+   * @param {string} billPaymentNo
+   */
+  validateVendorNotModified(
+    billPaymentDTO: IBillPaymentDTO,
+    oldBillPayment: IBillPayment
+  ) {
+    if (billPaymentDTO.vendorId !== oldBillPayment.vendorId) {
+      throw new ServiceError(ERRORS.PAYMENT_NUMBER_SHOULD_NOT_MODIFY);
+    }
+  }
+
+  /**
+   * Transforms create/edit DTO to model.
+   * @param {number} tenantId
+   * @param {IBillPaymentDTO} billPaymentDTO - Bill payment.
+   * @param {IBillPayment} oldBillPayment - Old bill payment.
+   * @return {Promise<IBillPayment>}
+   */
+  async transformDTOToModel(
+    tenantId: number,
+    billPaymentDTO: IBillPaymentDTO,
+    oldBillPayment?: IBillPayment
+  ): Promise<IBillPayment> {
+    // Retrieve vendor details by the given vendor id.
+    const vendor = await this.vendorsService.getVendorByIdOrThrowError(
+      tenantId,
+      billPaymentDTO.vendorId
+    );
+
+    return {
+      amount: sumBy(billPaymentDTO.entries, 'paymentAmount'),
+      currencyCode: vendor.currencyCode,
+      ...formatDateFields(billPaymentDTO, ['paymentDate']),
+      entries: billPaymentDTO.entries,
+    };
+  }
+
   /**
    * Creates a new bill payment transcations and store it to the storage
    * with associated bills entries and journal transactions.
@@ -288,11 +331,11 @@ export default class BillPaymentsService {
     });
     const { BillPayment } = this.tenancy.models(tenantId);
 
-    const billPaymentObj = {
-      amount: sumBy(billPaymentDTO.entries, 'paymentAmount'),
-      ...formatDateFields(billPaymentDTO, ['paymentDate']),
-    };
-
+    // Transform create DTO to model object.
+    const billPaymentObj = await this.transformDTOToModel(
+      tenantId,
+      billPaymentDTO
+    );
     // Validate vendor existance on the storage.
     await this.getVendorOrThrowError(tenantId, billPaymentObj.vendorId);
 
@@ -301,7 +344,6 @@ export default class BillPaymentsService {
       tenantId,
       billPaymentObj.paymentAccountId
     );
-
     // Validate the payment number uniquiness.
     if (billPaymentObj.paymentNumber) {
       await this.validatePaymentNumber(tenantId, billPaymentObj.paymentNumber);
@@ -312,15 +354,13 @@ export default class BillPaymentsService {
       billPaymentObj.entries,
       billPaymentDTO.vendorId
     );
-
     // Validates the bills due payment amount.
     await this.validateBillsDueAmount(tenantId, billPaymentObj.entries);
 
     const billPayment = await BillPayment.query().insertGraphAndFetch({
-      ...omit(billPaymentObj, ['entries']),
-      entries: billPaymentDTO.entries,
+      ...billPaymentObj,
     });
-
+    // Triggers `onBillPaymentCreated` event.
     await this.eventDispatcher.dispatch(events.billPayment.onCreated, {
       tenantId,
       billPayment,
@@ -363,11 +403,14 @@ export default class BillPaymentsService {
       tenantId,
       billPaymentId
     );
-
-    const billPaymentObj = {
-      amount: sumBy(billPaymentDTO.entries, 'paymentAmount'),
-      ...formatDateFields(billPaymentDTO, ['paymentDate']),
-    };
+    // Transform bill payment DTO to model object.
+    const billPaymentObj = await this.transformDTOToModel(
+      tenantId,
+      billPaymentDTO,
+      oldBillPayment
+    );
+    // Validate vendor not modified.
+    this.validateVendorNotModified(billPaymentDTO, oldBillPayment);
 
     // Validate vendor existance on the storage.
     await this.getVendorOrThrowError(tenantId, billPaymentObj.vendorId);
@@ -377,28 +420,24 @@ export default class BillPaymentsService {
       tenantId,
       billPaymentObj.paymentAccountId
     );
-
     // Validate the items entries IDs existance on the storage.
     await this.validateEntriesIdsExistance(
       tenantId,
       billPaymentId,
       billPaymentObj.entries
     );
-
     // Validate the bills existance and associated to the given vendor.
     await this.validateBillsExistance(
       tenantId,
       billPaymentObj.entries,
       billPaymentDTO.vendorId
     );
-
     // Validates the bills due payment amount.
     await this.validateBillsDueAmount(
       tenantId,
       billPaymentObj.entries,
       oldBillPayment.entries
     );
-
     // Validate the payment number uniquiness.
     if (billPaymentObj.paymentNumber) {
       await this.validatePaymentNumber(
@@ -409,8 +448,7 @@ export default class BillPaymentsService {
     }
     const billPayment = await BillPayment.query().upsertGraphAndFetch({
       id: billPaymentId,
-      ...omit(billPaymentObj, ['entries']),
-      entries: billPaymentDTO.entries,
+      ...billPaymentObj,
     });
     await this.eventDispatcher.dispatch(events.billPayment.onEdited, {
       tenantId,
diff --git a/server/src/services/Purchases/Bills.ts b/server/src/services/Purchases/Bills.ts
index bf3ab1137..5d2a716ff 100644
--- a/server/src/services/Purchases/Bills.ts
+++ b/server/src/services/Purchases/Bills.ts
@@ -27,6 +27,7 @@ import ItemsService from 'services/Items/ItemsService';
 import ItemsEntriesService from 'services/Items/ItemsEntriesService';
 import JournalCommands from 'services/Accounting/JournalCommands';
 import JournalPosterService from 'services/Sales/JournalPosterService';
+import VendorsService from 'services/Contacts/VendorsService';
 import { ERRORS } from './constants';
 
 /**
@@ -46,7 +47,7 @@ export default class BillsService extends SalesInvoicesCost {
 
   @Inject()
   tenancy: TenancyService;
-  
+
   @EventDispatcher()
   eventDispatcher: EventDispatcherInterface;
 
@@ -62,6 +63,9 @@ export default class BillsService extends SalesInvoicesCost {
   @Inject()
   journalPosterService: JournalPosterService;
 
+  @Inject()
+  vendorsService: VendorsService;
+
   /**
    * Validates whether the vendor is exist.
    * @async
@@ -136,16 +140,25 @@ export default class BillsService extends SalesInvoicesCost {
   }
 
   /**
-   * Converts bill DTO to model.
+   * Validate the bill number require.
+   * @param {string} billNo -
+   */
+  validateBillNoRequire(billNo: string) {
+    if (!billNo) {
+      throw new ServiceError(ERRORS.BILL_NO_IS_REQUIRED);
+    }
+  }
+
+  /**
+   * Converts create bill DTO to model.
    * @param {number} tenantId
    * @param {IBillDTO} billDTO
    * @param {IBill} oldBill
-   *
    * @returns {IBill}
    */
   private async billDTOToModel(
     tenantId: number,
-    billDTO: IBillDTO | IBillEditDTO,
+    billDTO: IBillDTO,
     authorizedUser: ISystemUser,
     oldBill?: IBill
   ) {
@@ -157,15 +170,25 @@ export default class BillsService extends SalesInvoicesCost {
     }));
     const amount = sumBy(entries, 'amount');
 
+    // Bill number from DTO or from auto-increment.
+    const billNumber = billDTO.billNumber || oldBill?.billNumber;
+
+    // Retrieve vendor details by the given vendor id.
+    const vendor = await this.vendorsService.getVendorByIdOrThrowError(
+      tenantId,
+      billDTO.vendorId
+    );
     return {
       ...formatDateFields(omit(billDTO, ['open', 'entries']), [
         'billDate',
         'dueDate',
       ]),
       amount,
+      currencyCode: vendor.currencyCode,
+      billNumber,
       entries: entries.map((entry) => ({
         reference_type: 'Bill',
-        ...omit(entry, ['amount', 'id']),
+        ...omit(entry, ['amount']),
       })),
       // Avoid rewrite the open date in edit mode when already opened.
       ...(billDTO.open &&
@@ -205,16 +228,14 @@ export default class BillsService extends SalesInvoicesCost {
     const billObj = await this.billDTOToModel(
       tenantId,
       billDTO,
-      authorizedUser,
-      null
+      authorizedUser
     );
     // Retrieve vendor or throw not found service error.
     await this.getVendorOrThrowError(tenantId, billDTO.vendorId);
 
     // Validate the bill number uniqiness on the storage.
-    if (billDTO.billNumber) {
-      await this.validateBillNumberExists(tenantId, billDTO.billNumber);
-    }
+    await this.validateBillNumberExists(tenantId, billDTO.billNumber);
+
     // Validate items IDs existance.
     await this.itemsEntriesService.validateItemsIdsExistance(
       tenantId,
@@ -277,7 +298,6 @@ export default class BillsService extends SalesInvoicesCost {
       authorizedUser,
       oldBill
     );
-
     // Retrieve vendor details or throw not found service error.
     await this.getVendorOrThrowError(tenantId, billDTO.vendorId);
 
@@ -292,7 +312,6 @@ export default class BillsService extends SalesInvoicesCost {
       'Bill',
       billDTO.entries
     );
-
     // Validate the items ids existance on the storage.
     await this.itemsEntriesService.validateItemsIdsExistance(
       tenantId,
diff --git a/server/src/services/Purchases/constants.ts b/server/src/services/Purchases/constants.ts
index e73fbb71b..b251516be 100644
--- a/server/src/services/Purchases/constants.ts
+++ b/server/src/services/Purchases/constants.ts
@@ -7,4 +7,5 @@ export const ERRORS = {
   BILL_ENTRIES_IDS_NOT_FOUND: 'BILL_ENTRIES_IDS_NOT_FOUND',
   NOT_PURCHASE_ABLE_ITEMS: 'NOT_PURCHASE_ABLE_ITEMS',
   BILL_ALREADY_OPEN: 'BILL_ALREADY_OPEN',
+  BILL_NO_IS_REQUIRED: 'BILL_NO_IS_REQUIRED'
 };
diff --git a/server/src/services/Sales/PaymentsReceives.ts b/server/src/services/Sales/PaymentsReceives.ts
index 29ee4f8ae..2a6acafbf 100644
--- a/server/src/services/Sales/PaymentsReceives.ts
+++ b/server/src/services/Sales/PaymentsReceives.ts
@@ -42,7 +42,9 @@ const ERRORS = {
   INVOICES_IDS_NOT_FOUND: 'INVOICES_IDS_NOT_FOUND',
   ENTRIES_IDS_NOT_EXISTS: 'ENTRIES_IDS_NOT_EXISTS',
   INVOICES_NOT_DELIVERED_YET: 'INVOICES_NOT_DELIVERED_YET',
-  PAYMENT_RECEIVE_NO_IS_REQUIRED: 'PAYMENT_RECEIVE_NO_IS_REQUIRED'
+  PAYMENT_RECEIVE_NO_IS_REQUIRED: 'PAYMENT_RECEIVE_NO_IS_REQUIRED',
+  PAYMENT_RECEIVE_NO_REQUIRED: 'PAYMENT_RECEIVE_NO_REQUIRED',
+  PAYMENT_CUSTOMER_SHOULD_NOT_UPDATE: 'PAYMENT_CUSTOMER_SHOULD_NOT_UPDATE',
 };
 /**
  * Payment receive service.
@@ -264,28 +266,6 @@ export default class PaymentReceiveService {
     }
   }
 
-  /**
-   * Retrieve estimate number to object model.
-   * @param {number} tenantId
-   * @param {IPaymentReceiveCreateDTO | IPaymentReceiveEditDTO} paymentReceiveDTO - Payment receive DTO.
-   * @param {IPaymentReceive} oldPaymentReceive - Old payment model object.
-   */
-  transformPaymentNumberToModel(
-    tenantId: number,
-    paymentReceiveDTO: IPaymentReceiveCreateDTO | IPaymentReceiveEditDTO,
-    oldPaymentReceive?: IPaymentReceive
-  ): string {
-    // Retreive the next invoice number.
-    const autoNextNumber = this.getNextPaymentReceiveNumber(tenantId);
-
-    if (paymentReceiveDTO.paymentReceiveNo) {
-      return paymentReceiveDTO.paymentReceiveNo;
-    }
-    return oldPaymentReceive
-      ? oldPaymentReceive.paymentReceiveNo
-      : autoNextNumber;
-  }
-
   /**
    * Validate the payment receive entries IDs existance.
    * @param {number} tenantId
@@ -315,32 +295,69 @@ export default class PaymentReceiveService {
     }
   }
 
+  /**
+   * Validates the payment receive number require.
+   * @param {string} paymentReceiveNo
+   */
+  validatePaymentNoRequire(paymentReceiveNo: string) {
+    if (!paymentReceiveNo) {
+      throw new ServiceError(ERRORS.PAYMENT_RECEIVE_NO_REQUIRED);
+    }
+  }
+
+  /**
+   * Validate the payment customer whether modified.
+   * @param {IPaymentReceiveEditDTO} paymentReceiveDTO
+   * @param {IPaymentReceive} oldPaymentReceive
+   */
+  validateCustomerNotModified(
+    paymentReceiveDTO: IPaymentReceiveEditDTO,
+    oldPaymentReceive: IPaymentReceive
+  ) {
+    if (paymentReceiveDTO.customerId !== oldPaymentReceive.customerId) {
+      throw new ServiceError(ERRORS.PAYMENT_CUSTOMER_SHOULD_NOT_UPDATE);
+    }
+  }
+
   /**
    * Transformes the create payment receive DTO to model object.
    * @param {number} tenantId
-   * @param {IPaymentReceiveCreateDTO} paymentReceiveDTO
+   * @param {IPaymentReceiveCreateDTO|IPaymentReceiveEditDTO} paymentReceiveDTO - Payment receive DTO.
+   * @param {IPaymentReceive} oldPaymentReceive -
+   * @return {IPaymentReceive}
    */
-  transformPaymentReceiveDTOToModel(
+  async transformPaymentReceiveDTOToModel(
     tenantId: number,
     paymentReceiveDTO: IPaymentReceiveCreateDTO | IPaymentReceiveEditDTO,
     oldPaymentReceive?: IPaymentReceive
-  ): IPaymentReceive {
+  ): Promise<IPaymentReceive> {
     const paymentAmount = sumBy(paymentReceiveDTO.entries, 'paymentAmount');
 
-    // Retrieve the next payment receive number.
-    const paymentReceiveNo = this.transformPaymentNumberToModel(
+    // Retrieve customer details.
+    const customer = await this.customersService.getCustomerByIdOrThrowError(
       tenantId,
-      paymentReceiveDTO,
-      oldPaymentReceive
+      paymentReceiveDTO.customerId
     );
+    // Retreive the next invoice number.
+    const autoNextNumber = this.getNextPaymentReceiveNumber(tenantId);
+
+    // Retrieve the next payment receive number.
+    const paymentReceiveNo =
+      paymentReceiveDTO.paymentReceiveNo ||
+      oldPaymentReceive?.paymentReceiveNo ||
+      autoNextNumber;
+
+    this.validatePaymentNoRequire(paymentReceiveNo);
+
     return {
       amount: paymentAmount,
+      currencyCode: customer.currencyCode,
       ...formatDateFields(omit(paymentReceiveDTO, ['entries']), [
         'paymentDate',
       ]),
       ...(paymentReceiveNo ? { paymentReceiveNo } : {}),
       entries: paymentReceiveDTO.entries.map((entry) => ({
-        ...omit(entry, ['id']),
+        ...entry,
       })),
     };
   }
@@ -360,13 +377,10 @@ export default class PaymentReceiveService {
     const { PaymentReceive } = this.tenancy.models(tenantId);
 
     // Transformes the payment receive DTO to model.
-    const paymentReceiveObj = this.transformPaymentReceiveDTOToModel(
+    const paymentReceiveObj = await this.transformPaymentReceiveDTOToModel(
       tenantId,
       paymentReceiveDTO
     );
-    // Validate payment receive is required.
-    this.validatePaymentReceiveNoRequire(paymentReceiveObj);
-
     // Validate payment receive number uniquiness.
     await this.validatePaymentReceiveNoExistance(
       tenantId,
@@ -393,7 +407,6 @@ export default class PaymentReceiveService {
       tenantId,
       paymentReceiveDTO.entries
     );
-
     this.logger.info('[payment_receive] inserting to the storage.');
     const paymentReceive = await PaymentReceive.query().insertGraphAndFetch({
       ...paymentReceiveObj,
@@ -447,13 +460,13 @@ export default class PaymentReceiveService {
       paymentReceiveId
     );
     // Transformes the payment receive DTO to model.
-    const paymentReceiveObj = this.transformPaymentReceiveDTOToModel(
+    const paymentReceiveObj = await this.transformPaymentReceiveDTOToModel(
       tenantId,
       paymentReceiveDTO,
       oldPaymentReceive
     );
-    // Validate payment receive number existance.
-    this.validatePaymentReceiveNoRequire(paymentReceiveObj);
+    // Validate customer whether modified.
+    this.validateCustomerNotModified(paymentReceiveDTO, oldPaymentReceive);
 
     // Validate payment receive number uniquiness.
     if (paymentReceiveDTO.paymentReceiveNo) {
@@ -527,7 +540,7 @@ export default class PaymentReceiveService {
     const { PaymentReceive, PaymentReceiveEntry } = this.tenancy.models(
       tenantId
     );
-
+    // Retreive payment receive or throw not found service error.
     const oldPaymentReceive = await this.getPaymentReceiveOrThrowError(
       tenantId,
       paymentReceiveId
diff --git a/server/src/services/Sales/SalesEstimate.ts b/server/src/services/Sales/SalesEstimate.ts
index b23edef53..b4022bdd2 100644
--- a/server/src/services/Sales/SalesEstimate.ts
+++ b/server/src/services/Sales/SalesEstimate.ts
@@ -31,7 +31,7 @@ const ERRORS = {
   SALE_ESTIMATE_ALREADY_REJECTED: 'SALE_ESTIMATE_ALREADY_REJECTED',
   SALE_ESTIMATE_ALREADY_APPROVED: 'SALE_ESTIMATE_ALREADY_APPROVED',
   SALE_ESTIMATE_NOT_DELIVERED: 'SALE_ESTIMATE_NOT_DELIVERED',
-  SALE_ESTIMATE_NO_IS_REQUIRED: 'SALE_ESTIMATE_NO_IS_REQUIRED'
+  SALE_ESTIMATE_NO_IS_REQUIRED: 'SALE_ESTIMATE_NO_IS_REQUIRED',
 };
 
 /**
@@ -157,25 +157,34 @@ export default class SaleEstimateService {
   }
 
   /**
-   * Transform DTO object ot model object.
+   * Transform create DTO object ot model object.
    * @param  {number} tenantId
-   * @param  {ISaleEstimateDTO} saleEstimateDTO
-   * @param  {ISaleEstimate} oldSaleEstimate
+   * @param  {ISaleEstimateDTO} saleEstimateDTO - Sale estimate DTO.
    * @return {ISaleEstimate}
    */
-  transformDTOToModel(
+  async transformDTOToModel(
     tenantId: number,
     estimateDTO: ISaleEstimateDTO,
     oldSaleEstimate?: ISaleEstimate
-  ): ISaleEstimate {
+  ): Promise<ISaleEstimate> {
     const { ItemEntry } = this.tenancy.models(tenantId);
     const amount = sumBy(estimateDTO.entries, (e) => ItemEntry.calcAmount(e));
 
+    // Retreive the next invoice number.
+    const autoNextNumber = this.getNextEstimateNumber(tenantId);
+
     // Retreive the next estimate number.
-    const estimateNumber = this.transformEstimateNumberToModel(
+    const estimateNumber = estimateDTO.estimateNumber ||
+      oldSaleEstimate?.estimateNumber ||
+      autoNextNumber;
+
+    // Validate the sale estimate number require.
+    this.validateEstimateNoRequire(estimateNumber);
+
+    // Retrieve customer details.
+    const customer = await this.customersService.getCustomerByIdOrThrowError(
       tenantId,
-      estimateDTO,
-      oldSaleEstimate
+      estimateDTO.customerId
     );
 
     return {
@@ -184,25 +193,26 @@ export default class SaleEstimateService {
         'estimateDate',
         'expirationDate',
       ]),
+      currencyCode: customer.currencyCode,
       ...(estimateNumber ? { estimateNumber } : {}),
       entries: estimateDTO.entries.map((entry) => ({
         reference_type: 'SaleEstimate',
-        ...omit(entry, ['total', 'amount', 'id']),
+        ...entry,
       })),
       // Avoid rewrite the deliver date in edit mode when already published.
       ...(estimateDTO.delivered &&
-        !oldSaleEstimate?.deliveredAt && {
-          deliveredAt: moment().toMySqlDateTime(),
-        }),
+          !oldSaleEstimate?.deliveredAt && {
+        deliveredAt: moment().toMySqlDateTime(),
+      }),
     };
   }
-  
+
   /**
    * Validate the sale estimate number require.
    * @param {ISaleEstimate} saleInvoiceObj
    */
-  validateEstimateNoRequire(saleInvoiceObj: ISaleEstimate) {
-    if (!saleInvoiceObj.estimateNumber) {
+  validateEstimateNoRequire(estimateNumber: string) {
+    if (!estimateNumber) {
       throw new ServiceError(ERRORS.SALE_ESTIMATE_NO_IS_REQUIRED);
     }
   }
@@ -223,27 +233,25 @@ export default class SaleEstimateService {
     this.logger.info('[sale_estimate] inserting sale estimate to the storage.');
 
     // Transform DTO object ot model object.
-    const estimateObj = this.transformDTOToModel(tenantId, estimateDTO);
-
-    // Validate the sale estimate number require.
-    this.validateEstimateNoRequire(estimateObj);
-
+    const estimateObj = await this.transformDTOToModel(
+      tenantId,
+      estimateDTO
+    );
     // Validate estimate number uniquiness on the storage.
-    if (estimateObj.estimateNumber) {
-      await this.validateEstimateNumberExistance(
-        tenantId,
-        estimateObj.estimateNumber
-      );
-    }
+    await this.validateEstimateNumberExistance(
+      tenantId,
+      estimateObj.estimateNumber
+    );
     // Retrieve the given customer or throw not found service error.
-    await this.customersService.getCustomer(tenantId, estimateDTO.customerId);
-
+    await this.customersService.getCustomerByIdOrThrowError(
+      tenantId,
+      estimateDTO.customerId
+    );
     // Validate items IDs existance on the storage.
     await this.itemsEntriesService.validateItemsIdsExistance(
       tenantId,
       estimateDTO.entries
     );
-
     // Validate non-sellable items.
     await this.itemsEntriesService.validateNonSellableEntriesItems(
       tenantId,
@@ -284,14 +292,11 @@ export default class SaleEstimateService {
       estimateId
     );
     // Transform DTO object ot model object.
-    const estimateObj = this.transformDTOToModel(
+    const estimateObj = await this.transformDTOToModel(
       tenantId,
       estimateDTO,
       oldSaleEstimate
     );
-    // Validate the sale estimate number require.
-    this.validateEstimateNoRequire(estimateObj);
-
     // Validate estimate number uniquiness on the storage.
     if (estimateDTO.estimateNumber) {
       await this.validateEstimateNumberExistance(
@@ -301,13 +306,15 @@ export default class SaleEstimateService {
       );
     }
     // Retrieve the given customer or throw not found service error.
-    await this.customersService.getCustomer(tenantId, estimateDTO.customerId);
-
+    await this.customersService.getCustomerByIdOrThrowError(
+      tenantId,
+      estimateDTO.customerId
+    );
     // Validate sale estimate entries existance.
     await this.itemsEntriesService.validateEntriesIdsExistance(
       tenantId,
       estimateId,
-      'SaleEstiamte',
+      'SaleEstimate',
       estimateDTO.entries
     );
     // Validate items IDs existance on the storage.
diff --git a/server/src/services/Sales/SalesInvoices.ts b/server/src/services/Sales/SalesInvoices.ts
index 3e68b2e17..36d6c586d 100644
--- a/server/src/services/Sales/SalesInvoices.ts
+++ b/server/src/services/Sales/SalesInvoices.ts
@@ -181,46 +181,36 @@ export default class SaleInvoicesService {
   }
 
   /**
-   * Retrieve invoice number to object model.
-   * @param tenantId 
-   * @param saleInvoiceDTO 
-   * @param oldSaleInvoice 
+   * Transformes the create DTO to invoice object model.
+   * @param {ISaleInvoiceCreateDTO} saleInvoiceDTO - Sale invoice DTO.
+   * @param {ISaleInvoice} oldSaleInvoice - Old sale invoice.
+   * @return {ISaleInvoice}
    */
-  transformInvoiceNumberToModel(
+  private async transformDTOToModel(
     tenantId: number,
     saleInvoiceDTO: ISaleInvoiceCreateDTO | ISaleInvoiceEditDTO,
     oldSaleInvoice?: ISaleInvoice
-  ): string {
-    // Retreive the next invoice number.
-    const autoNextNumber = this.getNextInvoiceNumber(tenantId);
-
-    if (saleInvoiceDTO.invoiceNo) {
-      return saleInvoiceDTO.invoiceNo;
-    }
-    return oldSaleInvoice ? oldSaleInvoice.invoiceNo : autoNextNumber;
-  }
-
-  /**
-   * Transform DTO object to model object.
-   * @param {number} tenantId - Tenant id.
-   * @param {ISaleInvoiceDTO} saleInvoiceDTO - Sale invoice DTO.
-   */
-  transformDTOToModel(
-    tenantId: number,
-    saleInvoiceDTO: ISaleInvoiceCreateDTO | ISaleInvoiceEditDTO,
-    oldSaleInvoice?: ISaleInvoice
-  ): ISaleInvoice {
+  ): Promise<ISaleInvoice> {
     const { ItemEntry } = this.tenancy.models(tenantId);
 
     const balance = sumBy(saleInvoiceDTO.entries, (e) =>
       ItemEntry.calcAmount(e)
     );
-
-    const invoiceNo = this.transformInvoiceNumberToModel(
+    // Retrieve customer details.
+    const customer = await this.customersService.getCustomerByIdOrThrowError(
       tenantId,
-      saleInvoiceDTO,
-      oldSaleInvoice
+      saleInvoiceDTO.customerId
     );
+    // Retreive the next invoice number.
+    const autoNextNumber = this.getNextInvoiceNumber(tenantId);
+
+    // Invoice number.
+    const invoiceNo =
+      saleInvoiceDTO.invoiceNo || oldSaleInvoice?.invoiceNo || autoNextNumber;
+
+    // Validate the invoice is required.
+    this.validateInvoiceNoRequire(invoiceNo);
+
     return {
       ...formatDateFields(
         omit(saleInvoiceDTO, ['delivered', 'entries', 'fromEstimateId']),
@@ -228,20 +218,17 @@ export default class SaleInvoicesService {
       ),
       // Avoid rewrite the deliver date in edit mode when already published.
       balance,
+      currencyCode: customer.currencyCode,
       ...(saleInvoiceDTO.delivered &&
         !oldSaleInvoice?.deliveredAt && {
           deliveredAt: moment().toMySqlDateTime(),
         }),
-      // Avoid add payment amount in edit mode.
-      ...(!oldSaleInvoice
-        ? {
-            paymentAmount: 0,
-          }
-        : {}),
+      // Avoid override payment amount in edit mode.
+      ...(!oldSaleInvoice && { paymentAmount: 0 }),
       ...(invoiceNo ? { invoiceNo } : {}),
       entries: saleInvoiceDTO.entries.map((entry) => ({
         referenceType: 'SaleInvoice',
-        ...omit(entry, ['amount', 'id']),
+        ...entry,
       })),
     };
   }
@@ -250,8 +237,8 @@ export default class SaleInvoicesService {
    * Validate the invoice number require.
    * @param {ISaleInvoice} saleInvoiceObj
    */
-  validateInvoiceNoRequire(saleInvoiceObj: ISaleInvoice) {
-    if (!saleInvoiceObj.invoiceNo) {
+  validateInvoiceNoRequire(invoiceNo: string) {
+    if (!invoiceNo) {
       throw new ServiceError(ERRORS.SALE_INVOICE_NO_IS_REQUIRED);
     }
   }
@@ -272,19 +259,15 @@ export default class SaleInvoicesService {
     const { saleInvoiceRepository } = this.tenancy.repositories(tenantId);
 
     // Transform DTO object to model object.
-    const saleInvoiceObj = this.transformDTOToModel(
+    const saleInvoiceObj = await this.transformDTOToModel(
       tenantId,
-      saleInvoiceDTO,
-      null
+      saleInvoiceDTO
     );
-    this.validateInvoiceNoRequire(saleInvoiceObj);
-
     // Validate customer existance.
     await this.customersService.getCustomerByIdOrThrowError(
       tenantId,
       saleInvoiceDTO.customerId
     );
-
     // Validate sale invoice number uniquiness.
     if (saleInvoiceObj.invoiceNo) {
       await this.validateInvoiceNumberUnique(
@@ -354,7 +337,7 @@ export default class SaleInvoicesService {
       saleInvoiceId
     );
     // Transform DTO object to model object.
-    const saleInvoiceObj = this.transformDTOToModel(
+    const saleInvoiceObj = await this.transformDTOToModel(
       tenantId,
       saleInvoiceDTO,
       oldSaleInvoice
@@ -396,10 +379,10 @@ export default class SaleInvoicesService {
     );
 
     this.logger.info('[sale_invoice] trying to update sale invoice.');
-    const saleInvoice: ISaleInvoice = await saleInvoiceRepository.update(
-      { ...omit(saleInvoiceObj, ['paymentAmount']) },
-      { id: saleInvoiceId }
-    );
+    const saleInvoice: ISaleInvoice = await saleInvoiceRepository.upsertGraph({
+      id: saleInvoiceId,
+      ...saleInvoiceObj,
+    });
     // Triggers `onSaleInvoiceEdited` event.
     await this.eventDispatcher.dispatch(events.saleInvoice.onEdited, {
       tenantId,
diff --git a/server/src/services/Sales/SalesReceipts.ts b/server/src/services/Sales/SalesReceipts.ts
index 4d6e1ddbd..bf5210239 100644
--- a/server/src/services/Sales/SalesReceipts.ts
+++ b/server/src/services/Sales/SalesReceipts.ts
@@ -20,6 +20,7 @@ import { ItemEntry } from 'models';
 import InventoryService from 'services/Inventory/Inventory';
 import { ACCOUNT_PARENT_TYPE } from 'data/AccountTypes';
 import AutoIncrementOrdersService from './AutoIncrementOrdersService';
+import CustomersService from 'services/Contacts/CustomersService';
 
 const ERRORS = {
   SALE_RECEIPT_NOT_FOUND: 'SALE_RECEIPT_NOT_FOUND',
@@ -27,7 +28,7 @@ const ERRORS = {
   DEPOSIT_ACCOUNT_NOT_CURRENT_ASSET: 'DEPOSIT_ACCOUNT_NOT_CURRENT_ASSET',
   SALE_RECEIPT_NUMBER_NOT_UNIQUE: 'SALE_RECEIPT_NUMBER_NOT_UNIQUE',
   SALE_RECEIPT_IS_ALREADY_CLOSED: 'SALE_RECEIPT_IS_ALREADY_CLOSED',
-  SALE_RECEIPT_NO_IS_REQUIRED: 'SALE_RECEIPT_NO_IS_REQUIRED'
+  SALE_RECEIPT_NO_IS_REQUIRED: 'SALE_RECEIPT_NO_IS_REQUIRED',
 };
 
 @Service()
@@ -56,6 +57,9 @@ export default class SalesReceiptService {
   @Inject()
   autoIncrementOrdersService: AutoIncrementOrdersService;
 
+  @Inject()
+  customersService: CustomersService;
+
   /**
    * Validate whether sale receipt exists on the storage.
    * @param {number} tenantId -
@@ -139,8 +143,8 @@ export default class SalesReceiptService {
    * Validate the sale receipt number require.
    * @param {ISaleReceipt} saleReceipt
    */
-  validateReceiptNoRequire(saleReceipt: ISaleReceipt) {
-    if (!saleReceipt.receiptNumber) {
+  validateReceiptNoRequire(receiptNumber: string) {
+    if (!receiptNumber) {
       throw new ServiceError(ERRORS.SALE_RECEIPT_NO_IS_REQUIRED);
     }
   }
@@ -189,40 +193,52 @@ export default class SalesReceiptService {
   }
 
   /**
-   * Transform DTO object to model object.
+   * Transform create DTO object to model object.
    * @param {ISaleReceiptDTO} saleReceiptDTO -
    * @param {ISaleReceipt} oldSaleReceipt -
    * @returns {ISaleReceipt}
    */
-  transformObjectDTOToModel(
+  async transformDTOToModel(
     tenantId: number,
     saleReceiptDTO: ISaleReceiptDTO,
     oldSaleReceipt?: ISaleReceipt
-  ): ISaleReceipt {
+  ): Promise<ISaleReceipt> {
     const amount = sumBy(saleReceiptDTO.entries, (e) =>
       ItemEntry.calcAmount(e)
     );
+    // Retreive the next invoice number.
+    const autoNextNumber = this.getNextReceiptNumber(tenantId);
+
     // Retreive the receipt number.
-    const receiptNumber = this.transformReceiptNumberToModel(
+    const receiptNumber =
+      saleReceiptDTO.receiptNumber ||
+      oldSaleReceipt?.receiptNumber ||
+      autoNextNumber;
+
+    // Validate receipt number require.
+    this.validateReceiptNoRequire(receiptNumber);
+
+    // Retrieve customer details.
+    const customer = await this.customersService.getCustomerByIdOrThrowError(
       tenantId,
-      saleReceiptDTO,
-      oldSaleReceipt
+      saleReceiptDTO.customerId
     );
 
     return {
       amount,
+      currencyCode: customer.currencyCode,
       ...formatDateFields(omit(saleReceiptDTO, ['closed', 'entries']), [
         'receiptDate',
       ]),
-      ...(receiptNumber ? { receiptNumber } : {}),
+      receiptNumber,
       // Avoid rewrite the deliver date in edit mode when already published.
       ...(saleReceiptDTO.closed &&
-        !oldSaleReceipt?.closedAt && {
+        !oldSaleReceipt.closedAt && {
           closedAt: moment().toMySqlDateTime(),
         }),
       entries: saleReceiptDTO.entries.map((entry) => ({
         reference_type: 'SaleReceipt',
-        ...omit(entry, ['id', 'amount']),
+        ...entry,
       })),
     };
   }
@@ -240,13 +256,10 @@ export default class SalesReceiptService {
     const { SaleReceipt } = this.tenancy.models(tenantId);
 
     // Transform sale receipt DTO to model.
-    const saleReceiptObj = this.transformObjectDTOToModel(
+    const saleReceiptObj = await this.transformDTOToModel(
       tenantId,
       saleReceiptDTO
     );
-    // Validate receipt number is required.
-    this.validateReceiptNoRequire(saleReceiptObj);
-
     // Validate receipt deposit account existance and type.
     await this.validateReceiptDepositAccountExistance(
       tenantId,
@@ -308,14 +321,11 @@ export default class SalesReceiptService {
       saleReceiptId
     );
     // Transform sale receipt DTO to model.
-    const saleReceiptObj = this.transformObjectDTOToModel(
+    const saleReceiptObj = await this.transformDTOToModel(
       tenantId,
       saleReceiptDTO,
       oldSaleReceipt
     );
-    // Validate receipt number is required.
-    this.validateReceiptNoRequire(saleReceiptObj);
-
     // Validate receipt deposit account existance and type.
     await this.validateReceiptDepositAccountExistance(
       tenantId,
diff --git a/server/src/subscribers/SaleReceipt/index.ts b/server/src/subscribers/SaleReceipt/index.ts
index b678f8d9d..d8b91b27d 100644
--- a/server/src/subscribers/SaleReceipt/index.ts
+++ b/server/src/subscribers/SaleReceipt/index.ts
@@ -3,17 +3,20 @@ import { On, EventSubscriber } from 'event-dispatch';
 import events from 'subscribers/events';
 import TenancyService from 'services/Tenancy/TenancyService';
 import SettingsService from 'services/Settings/SettingsService';
+import SalesReceiptService from 'services/Sales/SalesReceipts';
 
 @EventSubscriber()
 export default class SaleReceiptSubscriber {
   logger: any;
   tenancy: TenancyService;
   settingsService: SettingsService;
+  saleReceiptsService: SalesReceiptService;
 
   constructor() {
     this.logger = Container.get('logger');
     this.tenancy = Container.get(TenancyService);
     this.settingsService = Container.get(SettingsService);
+    this.saleReceiptsService = Container.get(SalesReceiptService);
   }
  
   /**
@@ -21,9 +24,6 @@ export default class SaleReceiptSubscriber {
    */
   @On(events.saleReceipt.onCreated)
   public async handleReceiptNextNumberIncrement({ tenantId, saleReceiptId }) {
-    await this.settingsService.incrementNextNumber(tenantId, {
-      key: 'next_number',
-      group: 'sales_receipts',
-    });
+    await this.saleReceiptsService.incrementNextReceiptNumber(tenantId);
   }
 }