diff --git a/packages/server/src/api/controllers/Cashflow/CashflowController.ts b/packages/server/src/api/controllers/Cashflow/CashflowController.ts
index c6dfe5c29..42efa4c48 100644
--- a/packages/server/src/api/controllers/Cashflow/CashflowController.ts
+++ b/packages/server/src/api/controllers/Cashflow/CashflowController.ts
@@ -13,9 +13,9 @@ export default class CashflowController {
   router() {
     const router = Router();
 
+    router.use(Container.get(CommandCashflowTransaction).router());
     router.use(Container.get(GetCashflowTransaction).router());
     router.use(Container.get(GetCashflowAccounts).router());
-    router.use(Container.get(CommandCashflowTransaction).router());
     router.use(Container.get(DeleteCashflowTransaction).router());
 
     return router;
diff --git a/packages/server/src/api/controllers/Cashflow/DeleteCashflowTransaction.ts b/packages/server/src/api/controllers/Cashflow/DeleteCashflowTransaction.ts
index 0ddb6d74d..4d94022da 100644
--- a/packages/server/src/api/controllers/Cashflow/DeleteCashflowTransaction.ts
+++ b/packages/server/src/api/controllers/Cashflow/DeleteCashflowTransaction.ts
@@ -3,14 +3,14 @@ import { Router, Request, Response, NextFunction } from 'express';
 import { param } from 'express-validator';
 import BaseController from '../BaseController';
 import { ServiceError } from '@/exceptions';
-import DeleteCashflowTransactionService from '../../../services/Cashflow/DeleteCashflowTransactionService';
+import { DeleteCashflowTransaction } from '../../../services/Cashflow/DeleteCashflowTransactionService';
 import CheckPolicies from '@/api/middleware/CheckPolicies';
 import { AbilitySubject, CashflowAction } from '@/interfaces';
 
 @Service()
-export default class DeleteCashflowTransaction extends BaseController {
+export default class DeleteCashflowTransactionController extends BaseController {
   @Inject()
-  deleteCashflowService: DeleteCashflowTransactionService;
+  private deleteCashflowService: DeleteCashflowTransaction;
 
   /**
    * Controller router.
diff --git a/packages/server/src/api/controllers/Cashflow/GetCashflowAccounts.ts b/packages/server/src/api/controllers/Cashflow/GetCashflowAccounts.ts
index 59fdb91ba..b84dad4eb 100644
--- a/packages/server/src/api/controllers/Cashflow/GetCashflowAccounts.ts
+++ b/packages/server/src/api/controllers/Cashflow/GetCashflowAccounts.ts
@@ -11,10 +11,10 @@ import { AbilitySubject, CashflowAction } from '@/interfaces';
 @Service()
 export default class GetCashflowAccounts extends BaseController {
   @Inject()
-  getCashflowAccountsService: GetCashflowAccountsService;
+  private getCashflowAccountsService: GetCashflowAccountsService;
 
   @Inject()
-  getCashflowTransactionsService: GetCashflowTransactionsService;
+  private getCashflowTransactionsService: GetCashflowTransactionsService;
 
   /**
    * Controller router.
diff --git a/packages/server/src/api/controllers/Cashflow/GetCashflowTransaction.ts b/packages/server/src/api/controllers/Cashflow/GetCashflowTransaction.ts
index 7cf8d2d8e..80d610f48 100644
--- a/packages/server/src/api/controllers/Cashflow/GetCashflowTransaction.ts
+++ b/packages/server/src/api/controllers/Cashflow/GetCashflowTransaction.ts
@@ -10,7 +10,7 @@ import { AbilitySubject, CashflowAction } from '@/interfaces';
 @Service()
 export default class GetCashflowAccounts extends BaseController {
   @Inject()
-  getCashflowTransactionsService: GetCashflowTransactionsService;
+  private getCashflowTransactionsService: GetCashflowTransactionsService;
 
   /**
    * Controller router.
diff --git a/packages/server/src/api/controllers/Cashflow/NewCashflowTransaction.ts b/packages/server/src/api/controllers/Cashflow/NewCashflowTransaction.ts
index 91abfcf92..9c48934ea 100644
--- a/packages/server/src/api/controllers/Cashflow/NewCashflowTransaction.ts
+++ b/packages/server/src/api/controllers/Cashflow/NewCashflowTransaction.ts
@@ -6,18 +6,27 @@ import { ServiceError } from '@/exceptions';
 import NewCashflowTransactionService from '@/services/Cashflow/NewCashflowTransactionService';
 import CheckPolicies from '@/api/middleware/CheckPolicies';
 import { AbilitySubject, CashflowAction } from '@/interfaces';
+import { CashflowApplication } from '@/services/Cashflow/CashflowApplication';
 
 @Service()
 export default class NewCashflowTransactionController extends BaseController {
   @Inject()
   private newCashflowTranscationService: NewCashflowTransactionService;
 
+  @Inject()
+  private cashflowApplication: CashflowApplication;
+
   /**
    * Router constructor.
    */
   public router() {
     const router = Router();
 
+    router.get(
+      '/transactions/uncategorized',
+      this.asyncMiddleware(this.getUncategorizedCashflowTransactions),
+      this.catchServiceErrors
+    );
     router.post(
       '/transactions',
       CheckPolicies(CashflowAction.Create, AbilitySubject.Cashflow),
@@ -26,13 +35,61 @@ export default class NewCashflowTransactionController extends BaseController {
       this.asyncMiddleware(this.newCashflowTransaction),
       this.catchServiceErrors
     );
+    router.post(
+      '/transactions/:id/uncategorize',
+      this.revertCategorizedCashflowTransaction,
+      this.catchServiceErrors
+    );
+    router.post(
+      '/transactions/:id/categorize',
+      this.categorizeCashflowTransactionValidationSchema,
+      this.validationResult,
+      this.categorizeCashflowTransaction,
+      this.catchServiceErrors
+    );
+    router.post(
+      '/transaction/:id/categorize/expense',
+      this.categorizeAsExpenseValidationSchema,
+      this.validationResult,
+      this.categorizesCashflowTransactionAsExpense,
+      this.catchServiceErrors
+    );
     return router;
   }
 
+  /**
+   * Categorize as expense validation schema.
+   */
+  public get categorizeAsExpenseValidationSchema() {
+    return [
+      check('expense_account_id').exists(),
+      check('date').isISO8601().exists(),
+      check('reference_no').optional(),
+      check('exchange_rate').optional().isFloat({ gt: 0 }).toFloat(),
+    ];
+  }
+
+  /**
+   * Categorize cashflow tranasction validation schema.
+   */
+  public get categorizeCashflowTransactionValidationSchema() {
+    return [
+      check('date').exists().isISO8601().toDate(),
+
+      check('to_account_id').exists().isInt().toInt(),
+      check('from_account_id').exists().isInt().toInt(),
+
+      check('transaction_type').exists(),
+      check('reference_no').optional(),
+      check('exchange_rate').optional().isFloat({ gt: 0 }).toFloat(),
+      check('description').optional(),
+    ];
+  }
+
   /**
    * New cashflow transaction validation schema.
    */
-  get newTransactionValidationSchema() {
+  public get newTransactionValidationSchema() {
     return [
       check('date').exists().isISO8601().toDate(),
       check('reference_no').optional({ nullable: true }).trim().escape(),
@@ -48,12 +105,10 @@ export default class NewCashflowTransactionController extends BaseController {
       check('credit_account_id').exists().isInt().toInt(),
 
       check('exchange_rate').optional().isFloat({ gt: 0 }).toFloat(),
-
       check('branch_id').optional({ nullable: true }).isNumeric().toInt(),
-
       check('publish').default(false).isBoolean().toBoolean(),
     ];
-  }
+  }√
 
   /**
    * Creates a new cashflow transaction.
@@ -76,7 +131,6 @@ export default class NewCashflowTransactionController extends BaseController {
           ownerContributionDTO,
           userId
         );
-
       return res.status(200).send({
         id: cashflowTransaction.id,
         message: 'New cashflow transaction has been created successfully.',
@@ -86,11 +140,118 @@ export default class NewCashflowTransactionController extends BaseController {
     }
   };
 
+  /**
+   * Revert the categorized cashflow transaction.
+   * @param {Request} req
+   * @param {Response} res
+   * @param {NextFunction} next
+   */
+  private revertCategorizedCashflowTransaction = async (
+    req: Request,
+    res: Response,
+    next: NextFunction
+  ) => {
+    const { tenantId } = req;
+    const { id: cashflowTransactionId } = req.params;
+
+    try {
+      const data= await this.cashflowApplication.uncategorizeTransaction(
+        tenantId,
+        cashflowTransactionId
+      );
+      return res.status(200).send({ data });
+    } catch (error) {
+      next(error);
+    }
+  };
+
+  /**
+   * Categorize the cashflow transaction.
+   * @param {Request} req
+   * @param {Response} res
+   * @param {NextFunction} next
+   */
+  private categorizeCashflowTransaction = async (
+    req: Request,
+    res: Response,
+    next: NextFunction
+  ) => {
+    const { tenantId } = req;
+    const { id: cashflowTransactionId } = req.params;
+    const cashflowTransaction = this.matchedBodyData(req);
+
+    try {
+      await this.cashflowApplication.categorizeTransaction(
+        tenantId,
+        cashflowTransactionId,
+        cashflowTransaction
+      );
+      return res.status(200).send({
+        message: 'The cashflow transaction has been created successfully.',
+      });
+    } catch (error) {
+      next(error);
+    }
+  };
+
+  /**
+   * Categorize the transaction as expense transaction.
+   * @param {Request} req
+   * @param {Response} res
+   * @param {NextFunction} next
+   */
+  private categorizesCashflowTransactionAsExpense = async (
+    req: Request,
+    res: Response,
+    next: NextFunction
+  ) => {
+    const { tenantId } = req;
+    const { id: cashflowTransactionId } = req.params;
+    const cashflowTransaction = this.matchedBodyData(req);
+
+    try {
+      await this.cashflowApplication.categorizeAsExpense(
+        tenantId,
+        cashflowTransactionId,
+        cashflowTransaction
+      );
+      return res.status(200).send({
+        message: 'The cashflow transaction has been created successfully.',
+      });
+    } catch (error) {
+      next(error);
+    }
+  };
+
+  /**
+   * Retrieves the uncategorized cashflow transactions.
+   * @param {Request} req 
+   * @param {Response} res 
+   * @param {NextFunction} next 
+   */
+  public getUncategorizedCashflowTransactions = async (
+    req: Request,
+    res: Response,
+    next: NextFunction
+  ) => {
+    const { tenantId } = req;
+    
+    try {
+      const data = await this.cashflowApplication.getUncategorizedTransactions(
+        tenantId
+      );
+
+      return res.status(200).send(data);
+    } catch (error) {
+      next(error);
+    }
+  };
+
   /**
    * Handle the service errors.
    * @param error
-   * @param req
-   * @param res
+   * @param {Request} req
+   * @param {res
    * @param next
    * @returns
    */
diff --git a/packages/server/src/database/migrations/20240228183404_create_uncateogrized_cashflow_transactions_table.js b/packages/server/src/database/migrations/20240228183404_create_uncateogrized_cashflow_transactions_table.js
new file mode 100644
index 000000000..2d72041f3
--- /dev/null
+++ b/packages/server/src/database/migrations/20240228183404_create_uncateogrized_cashflow_transactions_table.js
@@ -0,0 +1,25 @@
+exports.up = function (knex) {
+  return knex.schema.createTable(
+    'uncategorized_cashflow_transactions',
+    (table) => {
+      table.increments('id');
+      table.date('date').index();
+      table.decimal('amount');
+      table.string('reference_no').index();
+      table
+        .integer('account_id')
+        .unsigned()
+        .references('id')
+        .inTable('accounts');
+      table.string('description');
+      table.string('categorize_ref_type');
+      table.integer('categorize_ref_id').unsigned();
+      table.boolean('categorized').defaultTo(false);
+      table.timestamps();
+    }
+  );
+};
+
+exports.down = function (knex) {
+  return knex.schema.dropTableIfExists('uncategorized_cashflow_transactions');
+};
diff --git a/packages/server/src/database/migrations/20240228224316_add_categorized_transaction_id_column.js b/packages/server/src/database/migrations/20240228224316_add_categorized_transaction_id_column.js
new file mode 100644
index 000000000..749cc53b6
--- /dev/null
+++ b/packages/server/src/database/migrations/20240228224316_add_categorized_transaction_id_column.js
@@ -0,0 +1,11 @@
+exports.up = function (knex) {
+  return knex.schema.table('expenses_transactions', (table) => {
+    table
+      .integer('categorized_transaction_id')
+      .unsigned()
+      .references('id')
+      .inTable('uncategorized_cashflow_transactions');
+  });
+};
+
+exports.down = function (knex) {};
diff --git a/packages/server/src/interfaces/CashFlow.ts b/packages/server/src/interfaces/CashFlow.ts
index 40cd50896..8bcc1eafc 100644
--- a/packages/server/src/interfaces/CashFlow.ts
+++ b/packages/server/src/interfaces/CashFlow.ts
@@ -233,3 +233,27 @@ export interface ICashflowTransactionSchema {
 }
 
 export interface ICashflowTransactionInput extends ICashflowTransactionSchema {}
+
+export interface ICategorizeCashflowTransactioDTO {
+  fromAccountId: number;
+  toAccountId: number;
+  referenceNo: string;
+  transactionNumber: string;
+  transactionType: string;
+  exchangeRate: number;
+  description: string;
+  branchId: number;
+}
+
+export interface IUncategorizedCashflowTransaction {
+  id?: number;
+  amount: number;
+  date: Date;
+  currencyCode: string;
+  accountId: number;
+  description: string;
+  referenceNo: string;
+  categorizeRefType: string;
+  categorizeRefId: number;
+  categorized: boolean;
+}
diff --git a/packages/server/src/interfaces/CashflowService.ts b/packages/server/src/interfaces/CashflowService.ts
index e279aec05..5b446571d 100644
--- a/packages/server/src/interfaces/CashflowService.ts
+++ b/packages/server/src/interfaces/CashflowService.ts
@@ -1,5 +1,6 @@
 import { Knex } from 'knex';
 import { IAccount } from './Account';
+import { IUncategorizedCashflowTransaction } from './CashFlow';
 
 export interface ICashflowAccountTransactionsFilter {
   page: number;
@@ -124,8 +125,34 @@ export interface ICommandCashflowDeletedPayload {
   trx: Knex.Transaction;
 }
 
+export interface ICashflowTransactionCategorizedPayload {
+  tenantId: number;
+  cashflowTransactionId: number;
+  cashflowTransaction: ICashflowTransaction;
+  trx: Knex.Transaction;
+}
+export interface ICashflowTransactionUncategorizingPayload {
+  tenantId: number;
+  uncategorizedTransaction: IUncategorizedCashflowTransaction;
+  trx: Knex.Transaction;
+}
+export interface ICashflowTransactionUncategorizedPayload {
+  tenantId: number;
+  uncategorizedTransaction: IUncategorizedCashflowTransaction;
+  oldUncategorizedTransaction: IUncategorizedCashflowTransaction;
+  trx: Knex.Transaction;
+}
+
 export enum CashflowAction {
   Create = 'Create',
   Delete = 'Delete',
   View = 'View',
 }
+
+export interface CategorizeTransactionAsExpenseDTO {
+  expenseAccountId: number;
+  exchangeRate: number;
+  referenceNo: string;
+  description: string;
+  branchId?: number;
+}
diff --git a/packages/server/src/loaders/eventEmitter.ts b/packages/server/src/loaders/eventEmitter.ts
index 5e874a2ad..ccc28df3d 100644
--- a/packages/server/src/loaders/eventEmitter.ts
+++ b/packages/server/src/loaders/eventEmitter.ts
@@ -88,6 +88,7 @@ import { PlaidUpdateTransactionsOnItemCreatedSubscriber } from '@/services/Banki
 import { InvoiceChangeStatusOnMailSentSubscriber } from '@/services/Sales/Invoices/subscribers/InvoiceChangeStatusOnMailSentSubscriber';
 import { SaleReceiptMarkClosedOnMailSentSubcriber } from '@/services/Sales/Receipts/subscribers/SaleReceiptMarkClosedOnMailSentSubcriber';
 import { SaleEstimateMarkApprovedOnMailSent } from '@/services/Sales/Estimates/subscribers/SaleEstimateMarkApprovedOnMailSent';
+import { DeleteCashflowTransactionOnUncategorize } from '@/services/Cashflow/subscribers/DeleteCashflowTransactionOnUncategorize';
 
 export default () => {
   return new EventPublisher();
@@ -212,6 +213,9 @@ export const susbcribers = () => {
     SyncItemTaxRateOnEditTaxSubscriber,
 
     // Plaid
-    PlaidUpdateTransactionsOnItemCreatedSubscriber
+    PlaidUpdateTransactionsOnItemCreatedSubscriber,
+
+    // Cashflow
+    DeleteCashflowTransactionOnUncategorize,
   ];
 };
diff --git a/packages/server/src/loaders/tenantModels.ts b/packages/server/src/loaders/tenantModels.ts
index 2a3a3664f..c3d08ab6f 100644
--- a/packages/server/src/loaders/tenantModels.ts
+++ b/packages/server/src/loaders/tenantModels.ts
@@ -62,6 +62,7 @@ import TaxRate from 'models/TaxRate';
 import TaxRateTransaction from 'models/TaxRateTransaction';
 import Attachment from 'models/Attachment';
 import PlaidItem from 'models/PlaidItem';
+import UncategorizedCashflowTransaction from 'models/UncategorizedCashflowTransaction';
 
 export default (knex) => {
   const models = {
@@ -126,7 +127,8 @@ export default (knex) => {
     TaxRate,
     TaxRateTransaction,
     Attachment,
-    PlaidItem
+    PlaidItem,
+    UncategorizedCashflowTransaction
   };
   return mapValues(models, (model) => model.bindKnex(knex));
 };
diff --git a/packages/server/src/models/CashflowTransaction.ts b/packages/server/src/models/CashflowTransaction.ts
index d4743d4ce..4e47d0e2d 100644
--- a/packages/server/src/models/CashflowTransaction.ts
+++ b/packages/server/src/models/CashflowTransaction.ts
@@ -12,6 +12,7 @@ export default class CashflowTransaction extends TenantModel {
   transactionType: string;
   amount: number;
   exchangeRate: number;
+  uncategorize: boolean;
 
   /**
    * Table name.
diff --git a/packages/server/src/models/Expense.ts b/packages/server/src/models/Expense.ts
index ed756e2bb..967c9c734 100644
--- a/packages/server/src/models/Expense.ts
+++ b/packages/server/src/models/Expense.ts
@@ -182,6 +182,7 @@ export default class Expense extends mixin(TenantModel, [
     const ExpenseCategory = require('models/ExpenseCategory');
     const Media = require('models/Media');
     const Branch = require('models/Branch');
+    const UncategorizedCashflowTransaction = require('models/UncategorizedCashflowTransaction');
 
     return {
       paymentAccount: {
@@ -215,6 +216,10 @@ export default class Expense extends mixin(TenantModel, [
           to: 'branches.id',
         },
       },
+
+      /**
+       * 
+       */
       media: {
         relation: Model.ManyToManyRelation,
         modelClass: Media.default,
@@ -230,6 +235,18 @@ export default class Expense extends mixin(TenantModel, [
           query.where('model_name', 'Expense');
         },
       },
+
+      /**
+       * Retrieves the related uncategorized cashflow transaction.
+       */
+      categorized: {
+        relation: Model.BelongsToOneRelation,
+        modelClass: UncategorizedCashflowTransaction.default,
+        join: {
+          from: 'expenses_transactions.categorizedTransactionId',
+          to: 'uncategorized_cashflow_transactions.id',
+        },
+      }
     };
   }
 
diff --git a/packages/server/src/models/UncategorizedCashflowTransaction.ts b/packages/server/src/models/UncategorizedCashflowTransaction.ts
new file mode 100644
index 000000000..ed00be47e
--- /dev/null
+++ b/packages/server/src/models/UncategorizedCashflowTransaction.ts
@@ -0,0 +1,64 @@
+/* eslint-disable global-require */
+import TenantModel from 'models/TenantModel';
+import { Model } from 'objection';
+
+export default class UncategorizedCashflowTransaction extends TenantModel {
+  amount: number;
+  /**
+   * Table name.
+   */
+  static get tableName() {
+    return 'uncategorized_cashflow_transactions';
+  }
+
+  /**
+   * Timestamps columns.
+   */
+  static get timestamps() {
+    return ['createdAt', 'updatedAt'];
+  }
+
+  /**
+   * Retrieves the withdrawal amount.
+   * @returns {number}
+   */
+  public withdrawal() {
+    return this.amount > 0 ? Math.abs(this.amount) : 0;
+  }
+
+  /**
+   * Retrieves the deposit amount.
+   * @returns {number}
+   */
+  public deposit() {
+    return this.amount < 0 ? Math.abs(this.amount) : 0;
+  }
+
+  /**
+   * Virtual attributes.
+   */
+  static get virtualAttributes() {
+    return ['withdrawal', 'deposit'];
+  }
+
+  /**
+   * Relationship mapping.
+   */
+  static get relationMappings() {
+    const Account = require('models/Account');
+
+    return {
+      /**
+       * Transaction may has associated to account.
+       */
+      account: {
+        relation: Model.BelongsToOneRelation,
+        modelClass: Account.default,
+        join: {
+          from: 'uncategorized_cashflow_transactions.accountId',
+          to: 'accounts.id',
+        },
+      },
+    };
+  }
+}
diff --git a/packages/server/src/services/Banking/Plaid/PlaidSyncDB.ts b/packages/server/src/services/Banking/Plaid/PlaidSyncDB.ts
index 6f0260a2b..a9f9d14fd 100644
--- a/packages/server/src/services/Banking/Plaid/PlaidSyncDB.ts
+++ b/packages/server/src/services/Banking/Plaid/PlaidSyncDB.ts
@@ -9,7 +9,7 @@ import {
   transformPlaidTrxsToCashflowCreate,
 } from './utils';
 import NewCashflowTransactionService from '@/services/Cashflow/NewCashflowTransactionService';
-import DeleteCashflowTransactionService from '@/services/Cashflow/DeleteCashflowTransactionService';
+import { DeleteCashflowTransaction } from '@/services/Cashflow/DeleteCashflowTransactionService';
 import HasTenancyService from '@/services/Tenancy/TenancyService';
 
 const CONCURRENCY_ASYNC = 10;
@@ -26,7 +26,7 @@ export class PlaidSyncDb {
   private createCashflowTransactionService: NewCashflowTransactionService;
 
   @Inject()
-  private deleteCashflowTransactionService: DeleteCashflowTransactionService;
+  private deleteCashflowTransactionService: DeleteCashflowTransaction;
 
   /**
    * Syncs the plaid accounts to the system accounts.
diff --git a/packages/server/src/services/Cashflow/CashflowApplication.ts b/packages/server/src/services/Cashflow/CashflowApplication.ts
new file mode 100644
index 000000000..ee7548fee
--- /dev/null
+++ b/packages/server/src/services/Cashflow/CashflowApplication.ts
@@ -0,0 +1,104 @@
+import { Inject, Service } from 'typedi';
+import { DeleteCashflowTransaction } from './DeleteCashflowTransactionService';
+import { UncategorizeCashflowTransaction } from './UncategorizeCashflowTransaction';
+import { CategorizeCashflowTransaction } from './CategorizeCashflowTransaction';
+import {
+  CategorizeTransactionAsExpenseDTO,
+  ICategorizeCashflowTransactioDTO,
+} from '@/interfaces';
+import { CategorizeTransactionAsExpense } from './CategorizeTransactionAsExpense';
+import { GetUncategorizedTransactions } from './GetUncategorizedTransactions';
+
+@Service()
+export class CashflowApplication {
+  @Inject()
+  private deleteTransactionService: DeleteCashflowTransaction;
+
+  @Inject()
+  private uncategorizeTransactionService: UncategorizeCashflowTransaction;
+
+  @Inject()
+  private categorizeTransactionService: CategorizeCashflowTransaction;
+
+  @Inject()
+  private categorizeAsExpenseService: CategorizeTransactionAsExpense;
+
+  @Inject()
+  private getUncategorizedTransactionsService: GetUncategorizedTransactions;
+
+  /**
+   * Deletes the given cashflow transaction.
+   * @param {number} tenantId
+   * @param {number} cashflowTransactionId
+   * @returns
+   */
+  public deleteTransaction(tenantId: number, cashflowTransactionId: number) {
+    return this.deleteTransactionService.deleteCashflowTransaction(
+      tenantId,
+      cashflowTransactionId
+    );
+  }
+
+  /**
+   * Uncategorize the given cashflow transaction.
+   * @param {number} tenantId
+   * @param {number} cashflowTransactionId
+   * @returns
+   */
+  public uncategorizeTransaction(
+    tenantId: number,
+    cashflowTransactionId: number
+  ) {
+    return this.uncategorizeTransactionService.uncategorize(
+      tenantId,
+      cashflowTransactionId
+    );
+  }
+
+  /**
+   * Categorize the given cashflow transaction.
+   * @param {number} tenantId
+   * @param {number} cashflowTransactionId
+   * @param {ICategorizeCashflowTransactioDTO} categorizeDTO
+   * @returns
+   */
+  public categorizeTransaction(
+    tenantId: number,
+    cashflowTransactionId: number,
+    categorizeDTO: ICategorizeCashflowTransactioDTO
+  ) {
+    return this.categorizeTransactionService.categorize(
+      tenantId,
+      cashflowTransactionId,
+      categorizeDTO
+    );
+  }
+
+  /**
+   * Categorizes the given cashflow transaction as expense transaction.
+   * @param {number} tenantId
+   * @param {number} cashflowTransactionId
+   * @param {CategorizeTransactionAsExpenseDTO} transactionDTO
+   * @returns
+   */
+  public categorizeAsExpense(
+    tenantId: number,
+    cashflowTransactionId: number,
+    transactionDTO: CategorizeTransactionAsExpenseDTO
+  ) {
+    return this.categorizeAsExpenseService.categorize(
+      tenantId,
+      cashflowTransactionId,
+      transactionDTO
+    );
+  }
+
+  /**
+   * Retrieves the uncategorized cashflow transactions.
+   * @param {number} tenantId
+   * @returns {}
+   */
+  public getUncategorizedTransactions(tenantId: number) {
+    return this.getUncategorizedTransactionsService.getTransactions(tenantId);
+  }
+}
diff --git a/packages/server/src/services/Cashflow/CashflowTransactionJournalEntries.ts b/packages/server/src/services/Cashflow/CashflowTransactionJournalEntries.ts
index 21df84f34..c1c590d55 100644
--- a/packages/server/src/services/Cashflow/CashflowTransactionJournalEntries.ts
+++ b/packages/server/src/services/Cashflow/CashflowTransactionJournalEntries.ts
@@ -1,11 +1,9 @@
 import { Inject, Service } from 'typedi';
 import { Knex } from 'knex';
-import * as R from 'ramda';
 import {
   ILedgerEntry,
   ICashflowTransaction,
   AccountNormal,
-  ICashflowTransactionLine,
 } from '../../interfaces';
 import {
   transformCashflowTransactionType,
diff --git a/packages/server/src/services/Cashflow/CategorizeCashflowTransaction.ts b/packages/server/src/services/Cashflow/CategorizeCashflowTransaction.ts
new file mode 100644
index 000000000..e965afede
--- /dev/null
+++ b/packages/server/src/services/Cashflow/CategorizeCashflowTransaction.ts
@@ -0,0 +1,93 @@
+import { Inject, Service } from 'typedi';
+import HasTenancyService from '../Tenancy/TenancyService';
+import events from '@/subscribers/events';
+import { EventPublisher } from '@/lib/EventPublisher/EventPublisher';
+import UnitOfWork from '../UnitOfWork';
+import {
+  ICashflowTransactionCategorizedPayload,
+  ICashflowTransactionUncategorizingPayload,
+  ICategorizeCashflowTransactioDTO,
+} from '@/interfaces';
+import { Knex } from 'knex';
+import { transformCategorizeTransToCashflow } from './utils';
+import { CommandCashflowValidator } from './CommandCasflowValidator';
+import NewCashflowTransactionService from './NewCashflowTransactionService';
+
+@Service()
+export class CategorizeCashflowTransaction {
+  @Inject()
+  private tenancy: HasTenancyService;
+
+  @Inject()
+  private eventPublisher: EventPublisher;
+
+  @Inject()
+  private uow: UnitOfWork;
+
+  @Inject()
+  private commandValidators: CommandCashflowValidator;
+
+  @Inject()
+  private createCashflow: NewCashflowTransactionService;
+
+  /**
+   * Categorize the given cashflow transaction.
+   * @param {number} tenantId
+   * @param {ICategorizeCashflowTransactioDTO} categorizeDTO
+   */
+  public async categorize(
+    tenantId: number,
+    uncategorizedTransactionId: number,
+    categorizeDTO: ICategorizeCashflowTransactioDTO
+  ) {
+    const { UncategorizedCashflowTransaction } = this.tenancy.models(tenantId);
+
+    // Retrieves the uncategorized transaction or throw an error.
+    const transaction = await UncategorizedCashflowTransaction.query()
+      .findById(uncategorizedTransactionId)
+      .throwIfNotFound();
+
+    // Validates the transaction shouldn't be categorized before.
+    this.commandValidators.validateTransactionShouldNotCategorized(transaction);
+
+    // Edits the cashflow transaction under UOW env.
+    return this.uow.withTransaction(tenantId, async (trx: Knex.Transaction) => {
+      // Triggers `onTransactionCategorizing` event.
+      await this.eventPublisher.emitAsync(
+        events.cashflow.onTransactionCategorizing,
+        {
+          tenantId,
+          trx,
+        } as ICashflowTransactionUncategorizingPayload
+      );
+      // Transformes the categorize DTO to the cashflow transaction.
+      const cashflowTransactionDTO = transformCategorizeTransToCashflow(
+        transaction,
+        categorizeDTO
+      );
+      // Creates a new cashflow transaction.
+      const cashflowTransaction =
+        await this.createCashflow.newCashflowTransaction(
+          tenantId,
+          cashflowTransactionDTO
+        );
+      // Updates the uncategorized transaction as categorized.
+      await UncategorizedCashflowTransaction.query(trx)
+        .findById(uncategorizedTransactionId)
+        .patch({
+          categorized: true,
+          categorizeRefType: 'CashflowTransaction',
+          categorizeRefId: cashflowTransaction.id,
+        });
+      // Triggers `onCashflowTransactionCategorized` event.
+      await this.eventPublisher.emitAsync(
+        events.cashflow.onTransactionCategorized,
+        {
+          tenantId,
+          // cashflowTransaction,
+          trx,
+        } as ICashflowTransactionCategorizedPayload
+      );
+    });
+  }
+}
diff --git a/packages/server/src/services/Cashflow/CategorizeTransactionAsExpense.ts b/packages/server/src/services/Cashflow/CategorizeTransactionAsExpense.ts
new file mode 100644
index 000000000..119f0cc7b
--- /dev/null
+++ b/packages/server/src/services/Cashflow/CategorizeTransactionAsExpense.ts
@@ -0,0 +1,80 @@
+import {
+  CategorizeTransactionAsExpenseDTO,
+  ICashflowTransactionCategorizedPayload,
+} from '@/interfaces';
+import { Inject, Service } from 'typedi';
+import UnitOfWork from '../UnitOfWork';
+import events from '@/subscribers/events';
+import { EventPublisher } from '@/lib/EventPublisher/EventPublisher';
+import HasTenancyService from '../Tenancy/TenancyService';
+import { Knex } from 'knex';
+import { CreateExpense } from '../Expenses/CRUD/CreateExpense';
+
+@Service()
+export class CategorizeTransactionAsExpense {
+  @Inject()
+  private uow: UnitOfWork;
+
+  @Inject()
+  private tenancy: HasTenancyService;
+
+  @Inject()
+  private eventPublisher: EventPublisher;
+
+  @Inject()
+  private createExpenseService: CreateExpense;
+
+  /**
+   * Categorize the transaction as expense transaction.
+   * @param {number} tenantId
+   * @param {number} cashflowTransactionId
+   * @param {CategorizeTransactionAsExpenseDTO} transactionDTO
+   */
+  public async categorize(
+    tenantId: number,
+    cashflowTransactionId: number,
+    transactionDTO: CategorizeTransactionAsExpenseDTO
+  ) {
+    const { CashflowTransaction } = this.tenancy.models(tenantId);
+
+    const transaction = await CashflowTransaction.query()
+      .findById(cashflowTransactionId)
+      .throwIfNotFound();
+
+    return this.uow.withTransaction(tenantId, async (trx: Knex.Transaction) => {
+      // Triggers `onTransactionUncategorizing` event.
+      await this.eventPublisher.emitAsync(
+        events.cashflow.onTransactionCategorizingAsExpense,
+        {
+          tenantId,
+          trx,
+        } as ICashflowTransactionCategorizedPayload
+      );
+      // Creates a new expense transaction.
+      const expenseTransaction = await this.createExpenseService.newExpense(
+        tenantId,
+        {
+          
+        },
+        1
+      );
+      // Updates the item on the storage and fetches the updated once.
+      const cashflowTransaction = await CashflowTransaction.query(
+        trx
+      ).patchAndFetchById(cashflowTransactionId, {
+        categorizeRefType: 'Expense',
+        categorizeRefId: expenseTransaction.id,
+        uncategorized: true,
+      });
+      // Triggers `onTransactionUncategorized` event.
+      await this.eventPublisher.emitAsync(
+        events.cashflow.onTransactionCategorizedAsExpense,
+        {
+          tenantId,
+          cashflowTransaction,
+          trx,
+        } as ICashflowTransactionUncategorizedPayload
+      );
+    });
+  }
+}
diff --git a/packages/server/src/services/Cashflow/CommandCasflowValidator.ts b/packages/server/src/services/Cashflow/CommandCasflowValidator.ts
index 07722e50e..aabdc6301 100644
--- a/packages/server/src/services/Cashflow/CommandCasflowValidator.ts
+++ b/packages/server/src/services/Cashflow/CommandCasflowValidator.ts
@@ -4,6 +4,7 @@ import { IAccount } from '@/interfaces';
 import { getCashflowTransactionType } from './utils';
 import { ServiceError } from '@/exceptions';
 import { CASHFLOW_TRANSACTION_TYPE, ERRORS } from './constants';
+import CashflowTransaction from '@/models/CashflowTransaction';
 
 @Service()
 export class CommandCashflowValidator {
@@ -46,4 +47,28 @@ export class CommandCashflowValidator {
     }
     return transformedType;
   };
+
+  /**
+   * Validate the given transaction should be categorized.
+   * @param {CashflowTransaction} cashflowTransaction
+   */
+  public validateTransactionShouldCategorized(
+    cashflowTransaction: CashflowTransaction
+  ) {
+    if (!cashflowTransaction.uncategorize) {
+      throw new ServiceError(ERRORS.TRANSACTION_ALREADY_CATEGORIZED);
+    }
+  }
+
+  /**
+   * Validate the given transcation shouldn't be categorized.
+   * @param {CashflowTransaction} cashflowTransaction
+   */
+  public validateTransactionShouldNotCategorized(
+    cashflowTransaction: CashflowTransaction
+  ) {
+    if (cashflowTransaction.uncategorize) {
+      throw new ServiceError(ERRORS.TRANSACTION_ALREADY_CATEGORIZED);
+    }
+  }
 }
diff --git a/packages/server/src/services/Cashflow/DeleteCashflowTransactionService.ts b/packages/server/src/services/Cashflow/DeleteCashflowTransactionService.ts
index e07073c3d..dd6c3002a 100644
--- a/packages/server/src/services/Cashflow/DeleteCashflowTransactionService.ts
+++ b/packages/server/src/services/Cashflow/DeleteCashflowTransactionService.ts
@@ -13,15 +13,15 @@ import UnitOfWork from '@/services/UnitOfWork';
 import { EventPublisher } from '@/lib/EventPublisher/EventPublisher';
 
 @Service()
-export default class CommandCashflowTransactionService {
+export class DeleteCashflowTransaction {
   @Inject()
-  tenancy: HasTenancyService;
+  private tenancy: HasTenancyService;
 
   @Inject()
-  eventPublisher: EventPublisher;
+  private eventPublisher: EventPublisher;
 
   @Inject()
-  uow: UnitOfWork;
+  private uow: UnitOfWork;
 
   /**
    * Deletes the cashflow transaction with associated journal entries.
diff --git a/packages/server/src/services/Cashflow/GetCashflowTransactionsService.ts b/packages/server/src/services/Cashflow/GetCashflowTransactionsService.ts
index eb22dd305..13852dd05 100644
--- a/packages/server/src/services/Cashflow/GetCashflowTransactionsService.ts
+++ b/packages/server/src/services/Cashflow/GetCashflowTransactionsService.ts
@@ -4,7 +4,6 @@ import { CashflowTransactionTransformer } from './CashflowTransactionTransformer
 import { ERRORS } from './constants';
 import { ICashflowTransaction } from '@/interfaces';
 import { ServiceError } from '@/exceptions';
-import I18nService from '@/services/I18n/I18nService';
 import { TransformerInjectable } from '@/lib/Transformer/TransformerInjectable';
 
 @Service()
@@ -12,9 +11,6 @@ export default class GetCashflowTransactionsService {
   @Inject()
   private tenancy: HasTenancyService;
 
-  @Inject()
-  private i18nService: I18nService;
-
   @Inject()
   private transfromer: TransformerInjectable;
 
diff --git a/packages/server/src/services/Cashflow/GetUncategorizedTransactions.ts b/packages/server/src/services/Cashflow/GetUncategorizedTransactions.ts
new file mode 100644
index 000000000..955a5538a
--- /dev/null
+++ b/packages/server/src/services/Cashflow/GetUncategorizedTransactions.ts
@@ -0,0 +1,37 @@
+import { Inject, Service } from 'typedi';
+import HasTenancyService from '../Tenancy/TenancyService';
+import { TransformerInjectable } from '@/lib/Transformer/TransformerInjectable';
+import { UncategorizedTransactionTransformer } from './UncategorizedTransactionTransformer';
+
+@Service()
+export class GetUncategorizedTransactions {
+  @Inject()
+  private tenancy: HasTenancyService;
+
+  @Inject()
+  private transformer: TransformerInjectable;
+
+  /**
+   * Retrieves the uncategorized cashflow transactions.
+   * @param {number} tenantId
+   */
+  public async getTransactions(tenantId: number) {
+    const { UncategorizedCashflowTransaction } = this.tenancy.models(tenantId);
+
+    const { results, pagination } =
+      await UncategorizedCashflowTransaction.query()
+        .where('categorized', false)
+        .withGraphFetched('account')
+        .pagination(0, 10);
+
+    const data = await this.transformer.transform(
+      tenantId,
+      results,
+      new UncategorizedTransactionTransformer()
+    );
+    return {
+      data,
+      pagination,
+    };
+  }
+}
diff --git a/packages/server/src/services/Cashflow/NewCashflowTransactionService.ts b/packages/server/src/services/Cashflow/NewCashflowTransactionService.ts
index e8c53f5fc..5222a2664 100644
--- a/packages/server/src/services/Cashflow/NewCashflowTransactionService.ts
+++ b/packages/server/src/services/Cashflow/NewCashflowTransactionService.ts
@@ -1,11 +1,10 @@
 import { Service, Inject } from 'typedi';
-import { isEmpty, pick } from 'lodash';
+import { pick } from 'lodash';
 import { Knex } from 'knex';
 import * as R from 'ramda';
 import {
   ICashflowNewCommandDTO,
   ICashflowTransaction,
-  ICashflowTransactionLine,
   ICommandCashflowCreatedPayload,
   ICommandCashflowCreatingPayload,
   ICashflowTransactionInput,
@@ -126,7 +125,7 @@ export default class NewCashflowTransactionService {
     tenantId: number,
     newTransactionDTO: ICashflowNewCommandDTO,
     userId?: number
-  ): Promise<{ cashflowTransaction: ICashflowTransaction }> => {
+  ): Promise<ICashflowTransaction> => {
     const { CashflowTransaction, Account } = this.tenancy.models(tenantId);
 
     // Retrieves the cashflow account or throw not found error.
@@ -175,7 +174,7 @@ export default class NewCashflowTransactionService {
           trx,
         } as ICommandCashflowCreatedPayload
       );
-      return { cashflowTransaction };
+      return cashflowTransaction;
     });
   };
 }
diff --git a/packages/server/src/services/Cashflow/UncategorizeCashflowTransaction.ts b/packages/server/src/services/Cashflow/UncategorizeCashflowTransaction.ts
new file mode 100644
index 000000000..ba6740685
--- /dev/null
+++ b/packages/server/src/services/Cashflow/UncategorizeCashflowTransaction.ts
@@ -0,0 +1,72 @@
+import { Knex } from 'knex';
+import { Inject, Service } from 'typedi';
+import HasTenancyService from '../Tenancy/TenancyService';
+import UnitOfWork from '../UnitOfWork';
+import events from '@/subscribers/events';
+import { EventPublisher } from '@/lib/EventPublisher/EventPublisher';
+import {
+  ICashflowTransactionUncategorizedPayload,
+  ICashflowTransactionUncategorizingPayload,
+} from '@/interfaces';
+
+@Service()
+export class UncategorizeCashflowTransaction {
+  @Inject()
+  private tenancy: HasTenancyService;
+
+  @Inject()
+  private eventPublisher: EventPublisher;
+
+  @Inject()
+  private uow: UnitOfWork;
+
+  /**
+   * Uncategorizes the given cashflow transaction.
+   * @param {number} tenantId
+   * @param {number} cashflowTransactionId
+   */
+  public async uncategorize(
+    tenantId: number,
+    uncategorizedTransactionId: number
+  ) {
+    const { UncategorizedCashflowTransaction } = this.tenancy.models(tenantId);
+
+    const oldUncategorizedTransaction =
+      await UncategorizedCashflowTransaction.query()
+        .findById(uncategorizedTransactionId)
+        .throwIfNotFound();
+
+    // Updates the transaction under UOW.
+    return this.uow.withTransaction(tenantId, async (trx: Knex.Transaction) => {
+      // Triggers `onTransactionUncategorizing` event.
+      await this.eventPublisher.emitAsync(
+        events.cashflow.onTransactionUncategorizing,
+        {
+          tenantId,
+          trx,
+        } as ICashflowTransactionUncategorizingPayload
+      );
+      // Removes the ref relation with the related transaction.
+      const uncategorizedTransaction =
+        await UncategorizedCashflowTransaction.query(trx).updateAndFetchById(
+          uncategorizedTransactionId,
+          {
+            categorized: false,
+            categorizeRefId: null,
+            categorizeRefType: null,
+          }
+        );
+      // Triggers `onTransactionUncategorized` event.
+      await this.eventPublisher.emitAsync(
+        events.cashflow.onTransactionUncategorized,
+        {
+          tenantId,
+          uncategorizedTransaction,
+          oldUncategorizedTransaction,
+          trx,
+        } as ICashflowTransactionUncategorizedPayload
+      );
+      return uncategorizedTransaction;
+    });
+  }
+}
diff --git a/packages/server/src/services/Cashflow/UncategorizeTransactionByRef.ts b/packages/server/src/services/Cashflow/UncategorizeTransactionByRef.ts
new file mode 100644
index 000000000..f5590fb83
--- /dev/null
+++ b/packages/server/src/services/Cashflow/UncategorizeTransactionByRef.ts
@@ -0,0 +1,9 @@
+import { Service } from 'typedi';
+import { UncategorizeCashflowTransaction } from './UncategorizeCashflowTransaction';
+
+@Service()
+export class UncategorizeTransactionByRef {
+  private uncategorizeTransactionService: UncategorizeCashflowTransaction;
+
+  public uncategorize(tenantId: number, refId: number, refType: string) {}
+}
diff --git a/packages/server/src/services/Cashflow/UncategorizedTransactionTransformer.ts b/packages/server/src/services/Cashflow/UncategorizedTransactionTransformer.ts
new file mode 100644
index 000000000..2a4ceb4a4
--- /dev/null
+++ b/packages/server/src/services/Cashflow/UncategorizedTransactionTransformer.ts
@@ -0,0 +1,34 @@
+import { Transformer } from '@/lib/Transformer/Transformer';
+import { formatNumber } from '@/utils';
+
+export class UncategorizedTransactionTransformer extends Transformer {
+  /**
+   * Include these attributes to sale invoice object.
+   * @returns {string[]}
+   */
+  public includeAttributes = (): string[] => {
+    return ['formattetDepositAmount', 'formattedWithdrawalAmount'];
+  };
+
+  /**
+   * Formatted deposit amount.
+   * @param transaction
+   * @returns {string}
+   */
+  protected formattetDepositAmount(transaction) {
+    return formatNumber(transaction.deposit, {
+      currencyCode: transaction.currencyCode,
+    });
+  }
+
+  /**
+   * Formatted withdrawal amount.
+   * @param transaction
+   * @returns {string}
+   */
+  protected formattedWithdrawalAmount(transaction) {
+    return formatNumber(transaction.withdrawal, {
+      currencyCode: transaction.currencyCode,
+    });
+  }
+}
diff --git a/packages/server/src/services/Cashflow/constants.ts b/packages/server/src/services/Cashflow/constants.ts
index 2e664a519..4ec2d7004 100644
--- a/packages/server/src/services/Cashflow/constants.ts
+++ b/packages/server/src/services/Cashflow/constants.ts
@@ -8,7 +8,9 @@ export const ERRORS = {
   CREDIT_ACCOUNTS_IDS_NOT_FOUND: 'CREDIT_ACCOUNTS_IDS_NOT_FOUND',
   CREDIT_ACCOUNTS_HAS_INVALID_TYPE: 'CREDIT_ACCOUNTS_HAS_INVALID_TYPE',
   ACCOUNT_ID_HAS_INVALID_TYPE: 'ACCOUNT_ID_HAS_INVALID_TYPE',
-  ACCOUNT_HAS_ASSOCIATED_TRANSACTIONS: 'account_has_associated_transactions'
+  ACCOUNT_HAS_ASSOCIATED_TRANSACTIONS: 'account_has_associated_transactions',
+  TRANSACTION_ALREADY_CATEGORIZED: 'TRANSACTION_ALREADY_CATEGORIZED',
+  TRANSACTION_ALREADY_UNCATEGORIZED: 'TRANSACTION_ALREADY_UNCATEGORIZED'
 };
 
 export enum CASHFLOW_DIRECTION {
diff --git a/packages/server/src/services/Cashflow/subscribers/DeleteCashflowTransactionOnUncategorize.ts b/packages/server/src/services/Cashflow/subscribers/DeleteCashflowTransactionOnUncategorize.ts
new file mode 100644
index 000000000..3715b769c
--- /dev/null
+++ b/packages/server/src/services/Cashflow/subscribers/DeleteCashflowTransactionOnUncategorize.ts
@@ -0,0 +1,40 @@
+import { Inject, Service } from 'typedi';
+import events from '@/subscribers/events';
+import { ICashflowTransactionUncategorizedPayload } from '@/interfaces';
+import { DeleteCashflowTransaction } from '../DeleteCashflowTransactionService';
+
+@Service()
+export class DeleteCashflowTransactionOnUncategorize {
+  @Inject()
+  private deleteCashflowTransactionService: DeleteCashflowTransaction;
+
+  /**
+   * Attaches events with handlers.
+   */
+  public attach = (bus) => {
+    bus.subscribe(
+      events.cashflow.onTransactionUncategorized,
+      this.deleteCashflowTransactionOnUncategorize.bind(this)
+    );
+  };
+
+  /**
+   * Deletes the cashflow transaction on uncategorize transaction.
+   * @param {ICashflowTransactionUncategorizedPayload} payload
+   */
+  public async deleteCashflowTransactionOnUncategorize({
+    tenantId,
+    oldUncategorizedTransaction,
+    trx,
+  }: ICashflowTransactionUncategorizedPayload) {
+    // Deletes the cashflow transaction.
+    if (
+      oldUncategorizedTransaction.categorizeRefType === 'CashflowTransaction'
+    ) {
+      await this.deleteCashflowTransactionService.deleteCashflowTransaction(
+        tenantId,
+        oldUncategorizedTransaction.categorizeRefId
+      );
+    }
+  }
+}
diff --git a/packages/server/src/services/Cashflow/utils.ts b/packages/server/src/services/Cashflow/utils.ts
index 31af4b1bc..9d76f1862 100644
--- a/packages/server/src/services/Cashflow/utils.ts
+++ b/packages/server/src/services/Cashflow/utils.ts
@@ -1,13 +1,19 @@
-import { upperFirst, camelCase } from 'lodash';
+import { upperFirst, camelCase, omit } from 'lodash';
 import {
   CASHFLOW_TRANSACTION_TYPE,
   CASHFLOW_TRANSACTION_TYPE_META,
   ICashflowTransactionTypeMeta,
 } from './constants';
+import {
+  ICashflowNewCommandDTO,
+  ICashflowTransaction,
+  ICategorizeCashflowTransactioDTO,
+  IUncategorizedCashflowTransaction,
+} from '@/interfaces';
 
 /**
  * Ensures the given transaction type to transformed to appropriate format.
- * @param {string} type 
+ * @param {string} type
  * @returns {string}
  */
 export const transformCashflowTransactionType = (type) => {
@@ -32,3 +38,29 @@ export function getCashflowTransactionType(
 export const getCashflowAccountTransactionsTypes = () => {
   return Object.values(CASHFLOW_TRANSACTION_TYPE_META).map((meta) => meta.type);
 };
+
+/**
+ * Tranasformes the given uncategorized transaction and categorized DTO
+ * to cashflow create DTO.
+ * @param {IUncategorizedCashflowTransaction} uncategorizeModel 
+ * @param {ICategorizeCashflowTransactioDTO} categorizeDTO 
+ * @returns {ICashflowNewCommandDTO}
+ */
+export const transformCategorizeTransToCashflow = (
+  uncategorizeModel: IUncategorizedCashflowTransaction,
+  categorizeDTO: ICategorizeCashflowTransactioDTO
+): ICashflowNewCommandDTO => {
+  return {
+    date: uncategorizeModel.date,
+    referenceNo: categorizeDTO.referenceNo || uncategorizeModel.referenceNo,
+    description: categorizeDTO.description || uncategorizeModel.description,
+    cashflowAccountId: uncategorizeModel.accountId,
+    creditAccountId: categorizeDTO.fromAccountId || categorizeDTO.toAccountId,
+    exchangeRate: categorizeDTO.exchangeRate || 1,
+    currencyCode: uncategorizeModel.currencyCode,
+    amount: uncategorizeModel.amount,
+    transactionNumber: categorizeDTO.transactionNumber,
+    transactionType: categorizeDTO.transactionType,
+    publish: true,
+  };
+};
diff --git a/packages/server/src/subscribers/events.ts b/packages/server/src/subscribers/events.ts
index bae27d1a6..0243cd172 100644
--- a/packages/server/src/subscribers/events.ts
+++ b/packages/server/src/subscribers/events.ts
@@ -392,6 +392,15 @@ export default {
 
     onTransactionDeleting: 'onCashflowTransactionDeleting',
     onTransactionDeleted: 'onCashflowTransactionDeleted',
+
+    onTransactionCategorizing: 'onTransactionCategorizing',
+    onTransactionCategorized: 'onCashflowTransactionCategorized',
+
+    onTransactionUncategorizing: 'onTransactionUncategorizing',
+    onTransactionUncategorized: 'onTransactionUncategorized',
+
+    onTransactionCategorizingAsExpense: 'onTransactionCategorizingAsExpense',
+    onTransactionCategorizedAsExpense: 'onTransactionCategorizedAsExpense',
   },
 
   /**