diff --git a/app/models/transfer.rb b/app/models/transfer.rb
index 7d5c44947..3b60c1cfb 100644
--- a/app/models/transfer.rb
+++ b/app/models/transfer.rb
@@ -11,6 +11,7 @@ class Transfer < ApplicationRecord
   validate :transfer_has_opposite_amounts_or_fees
   validate :transfer_within_date_range
   validate :transfer_has_same_family
+  validate :fees_must_be_non_negative
 
   class << self
     def kind_for_account(account)
@@ -148,14 +149,19 @@ class Transfer < ApplicationRecord
       inflow_amount = inflow_entry.amount
       outflow_amount = outflow_entry.amount
 
+      errors.add(:base, :opposite_amounts) unless inflow_amount.negative? && outflow_amount.positive?
+
       if inflow_entry.currency == outflow_entry.currency
         total_fee = source_fee_amount.to_d + destination_fee_amount.to_d
         errors.add(:base, :opposite_amounts) if inflow_amount + outflow_amount != total_fee
-      else
-        errors.add(:base, :opposite_amounts) unless inflow_amount.negative? && outflow_amount.positive?
       end
     end
 
+    def fees_must_be_non_negative
+      errors.add(:source_fee_amount, :greater_than_or_equal_to, count: 0) if source_fee_amount.to_d.negative?
+      errors.add(:destination_fee_amount, :greater_than_or_equal_to, count: 0) if destination_fee_amount.to_d.negative?
+    end
+
     def transfer_within_date_range
       return unless inflow_transaction&.entry && outflow_transaction&.entry
 
diff --git a/app/views/transfers/show.html.erb b/app/views/transfers/show.html.erb
index 6b4a82afd..5b713b54a 100644
--- a/app/views/transfers/show.html.erb
+++ b/app/views/transfers/show.html.erb
@@ -35,13 +35,13 @@
           </dl>
           <dl class="flex items-center gap-2 justify-between">
             <dt class="text-secondary"><%= t(".amount") %></dt>
-            <dd class="font-medium text-red-500 privacy-sensitive"><%= format_money @transfer.outflow_transaction.entry.amount_money * -1 %></dd>
+            <dd class="font-medium text-destructive privacy-sensitive"><%= format_money @transfer.outflow_transaction.entry.amount_money * -1 %></dd>
           </dl>
         </div>
         <% if @transfer.has_source_fee? %>
           <dl class="flex items-center gap-2 justify-between">
             <dt class="text-secondary"><%= t(".source_fee") %></dt>
-            <dd class="font-medium text-red-500 privacy-sensitive">
+            <dd class="font-medium text-destructive privacy-sensitive">
               -<%= format_money Money.new(@transfer.source_fee_amount, @transfer.from_account.currency) %>
             </dd>
           </dl>
@@ -50,7 +50,7 @@
         <% if @transfer.has_destination_fee? %>
           <dl class="flex items-center gap-2 justify-between">
             <dt class="text-secondary"><%= t(".destination_fee") %></dt>
-            <dd class="font-medium text-red-500 privacy-sensitive">
+            <dd class="font-medium text-destructive privacy-sensitive">
               -<%= format_money Money.new(@transfer.destination_fee_amount, @transfer.to_account.currency) %>
             </dd>
           </dl>
@@ -71,7 +71,7 @@
           </dl>
           <dl class="flex items-center gap-2 justify-between">
             <dt class="text-secondary"><%= t(".amount") %></dt>
-            <dd class="font-medium text-green-500 privacy-sensitive">+<%= format_money @transfer.inflow_transaction.entry.amount_money * -1 %></dd>
+            <dd class="font-medium text-success privacy-sensitive">+<%= format_money @transfer.inflow_transaction.entry.amount_money * -1 %></dd>
           </dl>
         </div>
       </div>
@@ -115,7 +115,7 @@
           <%= button_to t(".delete"),
                 transfer_path(@transfer),
                 method: :delete,
-                class:  "rounded-lg px-3 py-2 whitespace-nowrap text-red-500 text-sm
+                class:  "rounded-lg px-3 py-2 whitespace-nowrap text-destructive text-sm
                           font-medium border border-secondary",
                 data:   { turbo_confirm: true, turbo_frame: "_top" } %>
         </div>
diff --git a/test/models/transfer_test.rb b/test/models/transfer_test.rb
index f59293096..f2abc4df9 100644
--- a/test/models/transfer_test.rb
+++ b/test/models/transfer_test.rb
@@ -203,4 +203,47 @@ class TransferTest < ActiveSupport::TestCase
     transfer.update!(source_fee_amount: 3, destination_fee_amount: 2)
     assert_equal 5, transfer.total_fee
   end
+
+  test "destination fee larger than amount inverts inflow sign and fails validation" do
+    outflow_entry = create_transaction(date: Date.current, account: accounts(:depository), amount: 100)
+    inflow_entry = create_transaction(date: Date.current, account: accounts(:credit_card), amount: 50)
+
+    transfer = Transfer.new(
+      inflow_transaction: inflow_entry.transaction,
+      outflow_transaction: outflow_entry.transaction,
+      destination_fee_amount: 150
+    )
+
+    # inflow amount (50) is positive, which means destination is also outflowing
+    assert transfer.invalid?
+    assert_equal "Must have opposite amounts", transfer.errors.full_messages.first
+  end
+
+  test "negative source fee is rejected" do
+    outflow_entry = create_transaction(date: Date.current, account: accounts(:depository), amount: 500)
+    inflow_entry = create_transaction(date: Date.current, account: accounts(:credit_card), amount: -500)
+
+    transfer = Transfer.new(
+      inflow_transaction: inflow_entry.transaction,
+      outflow_transaction: outflow_entry.transaction,
+      source_fee_amount: -5
+    )
+
+    assert transfer.invalid?
+    assert_equal [ "Source fee amount must be greater than or equal to 0" ], transfer.errors.full_messages
+  end
+
+  test "negative destination fee is rejected" do
+    outflow_entry = create_transaction(date: Date.current, account: accounts(:depository), amount: 500)
+    inflow_entry = create_transaction(date: Date.current, account: accounts(:credit_card), amount: -500)
+
+    transfer = Transfer.new(
+      inflow_transaction: inflow_entry.transaction,
+      outflow_transaction: outflow_entry.transaction,
+      destination_fee_amount: -5
+    )
+
+    assert transfer.invalid?
+    assert_equal [ "Destination fee amount must be greater than or equal to 0" ], transfer.errors.full_messages
+  end
 end