diff --git a/app/Services/ImportProcessor.php b/app/Services/ImportProcessor.php
index d5233db..b24d898 100644
--- a/app/Services/ImportProcessor.php
+++ b/app/Services/ImportProcessor.php
@@ -1346,7 +1346,12 @@ private function upsertAccount(Import $import, array $mapped, $mappings): array
                 $applyInsert[$field] = $value;
             }
             if (in_array($mode, ['update', 'both'])) {
-                $applyUpdate[$field] = $value;
+                // Do not allow updating initial_amount when mapping is update-only
+                if ($field === 'initial_amount' && $mode === 'update') {
+                    // skip: initial_amount can change only on insert, or when mapping mode is 'both'
+                } else {
+                    $applyUpdate[$field] = $value;
+                }
             }
         }