diff --git a/koha-tmpl/intranet-tmpl/prog/en/modules/pos/register.tt b/koha-tmpl/intranet-tmpl/prog/en/modules/pos/register.tt
index e449fef31c..828ac21e6d 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/modules/pos/register.tt
+++ b/koha-tmpl/intranet-tmpl/prog/en/modules/pos/register.tt
@@ -286,8 +286,10 @@
         </div>
     </div><!-- /.row -->
 
-    <!-- Confirm cashup modal -->
-    <div class="modal" id="confirmCashupModal" tabindex="-1" role="dialog" aria-labelledby="confirmCashupLabel">
+<!-- Confirm cashup modal -->
+<div class="modal" id="confirmCashupModal" tabindex="-1" role="dialog" aria-labelledby="confirmCashupLabel">
+    <form id="cashup_form" method="post" enctype="multipart/form-data">
+        [% INCLUDE 'csrf-token.inc' %]
         <div class="modal-dialog">
             <div class="modal-content">
                 <div class="modal-header">
@@ -296,14 +298,22 @@
                 </div>
                 <div class="modal-body">
                     Please confirm that you have removed [% accountlines.total( payment_type => [ 'CASH', 'SIP00' ]) * -1 | $Price %] from the cash register and left a float of [% register.starting_float | $Price %].
-                </div> <!-- /.modal-body -->
+                </div>
+                <!-- /.modal-body -->
                 <div class="modal-footer">
-                    <a href="/cgi-bin/koha/pos/register.pl?op=cashup" class="btn btn-primary" id="pos_cashup_confirm">Confirm</a>
+                    <input type="hidden" name="registerid" value="[% register.id | html %]" />
+                    <input type="hidden" name="op" value="cud-cashup" />
+                    <button type="submit" class="btn btn-primary" id="pos_cashup_confirm">Confirm</button>
                     <button type="button" class="btn btn-default" data-bs-dismiss="modal">Cancel</button>
-                </div> <!-- /.modal-footer -->
-            </div> <!-- /.modal-content -->
-        </div> <!-- /.modal-dialog -->
-    </div> <!-- /#confirmCashupModal -->
+                </div>
+                <!-- /.modal-footer -->
+            </div>
+            <!-- /.modal-content -->
+        </div>
+        <!-- /.modal-dialog -->
+    </form>
+</div>
+<!-- /#confirmCashupModal -->
 
     <!-- Issue refund modal -->
     <div class="modal" id="issueRefundModal" tabindex="-1" role="dialog" aria-labelledby="issueRefundLabel">
diff --git a/koha-tmpl/intranet-tmpl/prog/en/modules/pos/registers.tt b/koha-tmpl/intranet-tmpl/prog/en/modules/pos/registers.tt
index be750d4e5e..2544ab1b39 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/modules/pos/registers.tt
+++ b/koha-tmpl/intranet-tmpl/prog/en/modules/pos/registers.tt
@@ -151,47 +151,64 @@
         </div>
         <!-- /.row -->
 
-        <!-- Confirm cashup modal -->
-        <div class="modal" id="confirmCashupModal" tabindex="-1" role="dialog" aria-labelledby="confirmCashupLabel">
-            <div class="modal-dialog">
-                <div class="modal-content">
-                    <div class="modal-header">
-                        <h1 class="modal-title" id="confirmCashupLabel">Confirm cashup of <em><span id="registerc"></span></em></h1>
-                        <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
-                    </div>
-                    <div class="modal-body">
-                        Please confirm that you have removed <span id="cashc"></span> from the cash register and left a float of <span id="floatc"></span>.
-                    </div> <!-- /.modal-body -->
-                    <div class="modal-footer">
-                        <a id="cashup_confirm" href="" class="btn btn-primary">Confirm</a>
-                        <button type="button" class="btn btn-default" data-bs-dismiss="modal">Cancel</button>
-                    </div> <!-- /.modal-footer -->
-                </div> <!-- /.modal-content -->
-            </div> <!-- /.modal-dialog -->
-        </div> <!-- /#confirmCashupModal -->
+<!-- Confirm cashup modal -->
+<div class="modal" id="confirmCashupModal" tabindex="-1" role="dialog" aria-labelledby="confirmCashupLabel">
+    <form id="cashup_individual_form" method="post" enctype="multipart/form-data">
+        [% INCLUDE 'csrf-token.inc' %]
+        <div class="modal-dialog">
+            <div class="modal-content">
+                <div class="modal-header">
+                    <h1 class="modal-title" id="confirmCashupLabel">Confirm cashup of <em><span id="registerc"></span></em></h1>
+                    <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
+                </div>
+                <div class="modal-body">
+                    Please confirm that you have removed <span id="cashc"></span> from the cash register and left a float of <span id="floatc"></span>.
+                </div> <!-- /.modal-body -->
+                <div class="modal-footer">
+                    <input type="hidden" name="registerid" id="cashup_registerid" value="" />
+                    <input type="hidden" name="op" value="cud-cashup" />
+                    <button type="submit" class="btn btn-primary" id="cashup_confirm">Confirm</button>
+                    <button type="button" class="btn btn-default" data-bs-dismiss="modal">Cancel</button>
+                </div>
+                <!-- /.modal-footer -->
+            </div>
+        <!-- /.modal-content -->
+        </div>
+        <!-- /.modal-dialog -->
+    </form>
+</div>
+<!-- /#confirmCashupModal -->
 
-        <!-- Confirm cashupall modal -->
-        <div class="modal" id="confirmCashupAllModal" tabindex="-1" role="dialog" aria-labelledby="confirmCashupAllLabel">
-            <div class="modal-dialog">
-                <div class="modal-content">
-                    <div class="modal-header">
-                        <h1 class="modal-title" id="confirmCashupAllLabel">Confirm cashup of <em>all</em> cash registers</h1>
-                        <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
-                    </div>
-                    <div class="modal-body">
-                        <p>Please confirm that you have received [% bankable | $Price %] to cashup.</p>
-                        <ul>
-                            <li>Total income (cash): [% ctotal | $Price %] ([% cctotal | $Price %])</li>
-                            <li>Total outgoing (cash): [% dtotal | $Price %] ([% cdtotal | $Price %])</li>
-                        </ul>
-                    </div> <!-- /.modal-body -->
-                    <div class="modal-footer">
-                        <a id="cashup_all_confirm" href="/cgi-bin/koha/pos/registers.pl?op=cashup" class="btn btn-primary">Confirm</a>
-                        <button type="button" class="btn btn-default" data-bs-dismiss="modal">Cancel</button>
-                    </div> <!-- /.modal-footer -->
-                </div> <!-- /.modal-content -->
-            </div> <!-- /.modal-dialog -->
-        </div> <!-- /#confirmCashupAllModal -->
+<!-- Confirm cashupall modal -->
+<div class="modal" id="confirmCashupAllModal" tabindex="-1" role="dialog" aria-labelledby="confirmCashupAllLabel">
+    <form id="cashup_all_form" method="post" enctype="multipart/form-data">
+        [% INCLUDE 'csrf-token.inc' %]
+        <div class="modal-dialog">
+            <div class="modal-content">
+                <div class="modal-header">
+                    <h1 class="modal-title" id="confirmCashupAllLabel">Confirm cashup of <em>all</em> cash registers</h1>
+                    <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
+                </div>
+                <div class="modal-body">
+                    <p>Please confirm that you have received [% bankable | $Price %] to cashup.</p>
+                    <ul>
+                        <li>Total income (cash): [% ctotal | $Price %] ([% cctotal | $Price %])</li>
+                        <li>Total outgoing (cash): [% dtotal | $Price %] ([% cdtotal | $Price %])</li>
+                    </ul>
+                </div> <!-- /.modal-body -->
+                <div class="modal-footer">
+                    <input type="hidden" name="op" value="cud-cashup" />
+                    <button type="submit" class="btn btn-primary" id="cashup_all_confirm">Confirm</button>
+                    <button type="button" class="btn btn-default" data-bs-dismiss="modal">Cancel</button>
+                </div>
+                <!-- /.modal-footer -->
+            </div>
+            <!-- /.modal-content -->
+        </div>
+        <!-- /.modal-dialog -->
+    </form>
+</div>
+<!-- /#confirmCashupAllModal -->
 
         [% INCLUDE 'modals/cashup_summary.inc' %]
 
@@ -223,7 +240,7 @@
                    var rfloat = button.data('float');
                    $('#floatc').text(rfloat);
                    var rid = button.data('registerid');
-                   $('#cashup_confirm').attr("href", '/cgi-bin/koha/pos/registers.pl?op=cashup&registerid='+rid);
+                   $('#cashup_registerid').val(rid);
                 });
             });
         </script>
diff --git a/pos/register.pl b/pos/register.pl
index 53bb5d2325..7ab0f887ff 100755
--- a/pos/register.pl
+++ b/pos/register.pl
@@ -104,7 +104,7 @@ else {
     $template->param( trange_t => $end, );
 
     my $op = $input->param('op') // '';
-    if ( $op eq 'cashup' ) {
+    if ( $op eq 'cud-cashup' ) {
         if ( $logged_in_user->has_permission( { cash_management => 'cashup' } ) ) {
             $cash_register->add_cashup(
                 {
@@ -112,8 +112,11 @@ else {
                     amount     => $cash_register->outstanding_accountlines->total
                 }
             );
-        }
-        else {
+
+            # Redirect to prevent duplicate submissions (POST/REDIRECT/GET pattern)
+            print $input->redirect( "/cgi-bin/koha/pos/register.pl?registerid=" . $registerid );
+            exit;
+        } else {
             $template->param( error_cashup_permission => 1 );
         }
     }
diff --git a/pos/registers.pl b/pos/registers.pl
index 7a9c3a1699..80f14b0778 100755
--- a/pos/registers.pl
+++ b/pos/registers.pl
@@ -55,7 +55,7 @@ else {
 }
 
 my $op = $input->param('op') // '';
-if ( $op eq 'cashup' ) {
+if ( $op eq 'cud-cashup' ) {
     if ( $logged_in_user->has_permission( { cash_management => 'cashup' } ) ) {
         my $registerid = $input->param('registerid');
         if ($registerid) {
@@ -77,8 +77,11 @@ if ( $op eq 'cashup' ) {
                 );
             }
         }
-    }
-    else {
+
+        # Redirect to prevent duplicate submissions (POST/REDIRECT/GET pattern)
+        print $input->redirect("/cgi-bin/koha/pos/registers.pl");
+        exit;
+    } else {
         $template->param( error_cashup_permission => 1 );
     }
 }