diff --git a/app/Http/Controllers/Repuve/CancellationController.php b/app/Http/Controllers/Repuve/CancellationController.php
index 557ea40..8dfa66e 100644
--- a/app/Http/Controllers/Repuve/CancellationController.php
+++ b/app/Http/Controllers/Repuve/CancellationController.php
@@ -45,9 +45,6 @@ public function cancelarConstancia(CancelConstanciaRequest $request)
                 ]);
             }
 
-            // Avisar que tiene error
-            $hadPreviousError = $record->error_id !== null;
-
             // Guardar información del tag anterior ANTES de cancelarlo
             $oldTagNumber = $tag->tag_number;
             $oldFolio = $tag->folio;
@@ -69,10 +66,10 @@ public function cancelarConstancia(CancelConstanciaRequest $request)
 
             $newTag = null;
             $substitutionLog  = null;
-            $isSubstitution = $request->filled('new_tag_number');
+            $isSubstitution = $request->filled('new_folio') && $request->filled('new_tag_number');
 
             if ($isSubstitution) {
-                $newTag = Tag::where('tag_number', $request->new_tag_number)->first();
+                $newTag = Tag::where('folio', $request->new_folio)->first();
 
                 if(!$newTag){
                     DB::rollBack();
@@ -91,6 +88,31 @@ public function cancelarConstancia(CancelConstanciaRequest $request)
                     ]);
                 }
 
+                if(!$newTag->tag_number){
+                    $existingTag = Tag::where('tag_number', $request->new_tag_number)->first();
+                    if($existingTag && $existingTag->id !== $newTag->id){
+                        DB::rollBack();
+                        return ApiResponse::BAD_REQUEST->response([
+                            'message' => 'El nuevo tag_number ya está asignado a otro folio.',
+                            'new_tag_number' => $request->new_tag_number,
+                            'folio_existente' => $existingTag->folio,
+                        ]);
+
+                    }
+
+                    $newTag->tag_number = $request->new_tag_number;
+                    $newTag->save();
+
+                    }elseif($newTag->tag_number !== $request->new_tag_number){
+                        DB::rollBack();
+                        return ApiResponse::BAD_REQUEST->response([
+                            'message' => 'El nuevo tag ya tiene un tag_number diferente asignado.',
+                            'assigned_tag_number' => $newTag->tag_number,
+                            'provided_tag_number' => $request->new_tag_number,
+                        ]);
+
+                }
+
                 // Usar el folio del request
                 $newTag->markAsAssigned($vehicle->id, $request->folio);
 
@@ -160,14 +182,22 @@ public function cancelarTagNoAsignado(Request $request)
 {
     try {
         $request->validate([
-            'tag_number' => 'required|string|exists:tags,tag_number',
+            'folio' => 'required|string|exists:tags,folio',
             'cancellation_reason_id' => 'required|exists:catalog_cancellation_reasons,id',
             'cancellation_observations' => 'nullable|string',
         ]);
 
         DB::beginTransaction();
 
-        $tag = Tag::where('tag_number', $request->tag_number)->first();
+        $tag = Tag::where('folio', $request->folio)->first();
+
+        if (!$tag) {
+            DB::rollBack();
+            return ApiResponse::NOT_FOUND->response([
+                'message' => 'No se encontró el tag con el folio proporcionado.',
+                'folio' => $request->folio,
+            ]);
+        }
 
         // Validar que el tag NO esté asignado
         if ($tag->isAssigned()) {
diff --git a/app/Http/Controllers/Repuve/InscriptionController.php b/app/Http/Controllers/Repuve/InscriptionController.php
index c1f67c3..52fc120 100644
--- a/app/Http/Controllers/Repuve/InscriptionController.php
+++ b/app/Http/Controllers/Repuve/InscriptionController.php
@@ -45,7 +45,7 @@ public function vehicleInscription(VehicleStoreRequest $request)
             $telefono = $request->input('telefono');
 
             // Buscar Tag y validar que NO tenga vehículo asignado
-            $tag = Tag::where('folio', $folio)->where('tag_number', $tagNumber)->first();
+            $tag = Tag::where('folio', $folio)->first();
 
             if (!$tag) {
                 return ApiResponse::NOT_FOUND->response([
@@ -65,6 +65,30 @@ public function vehicleInscription(VehicleStoreRequest $request)
             // Iniciar transacción
             DB::beginTransaction();
 
+            if (!$tag->tag_number) {
+                $existingTag = Tag::where('tag_number', $tagNumber)->first();
+                if ($existingTag && $existingTag->id !== $tag->id) {
+                    DB::rollBack();
+                    return ApiResponse::BAD_REQUEST->response([
+                        'message' => 'El tag_number ya está asignado a otro folio.',
+                        'tag_number' => $tagNumber,
+                        'folio_existente' => $existingTag->folio,
+                    ]);
+                }
+                // Guardar tag_number
+                $tag->tag_number = $tagNumber;
+                $tag->save();
+            } elseif ($tag->tag_number !== $tagNumber) {
+                // Si el tag ya tiene un tag_number diferente, validar
+                DB::rollBack();
+                return ApiResponse::BAD_REQUEST->response([
+                    'message' => 'El folio ya tiene un tag_number diferente asignado.',
+                    'folio' => $folio,
+                    'tag_number_actual' => $tag->tag_number,
+                    'tag_number_enviado' => $tagNumber,
+                ]);
+            }
+
             $datosCompletosRaw = $this->padronEstatalService->getVehiculoByPlaca($placa);
 
             // Obtener datos de API Estatal por placa
diff --git a/app/Http/Controllers/Repuve/TagsController.php b/app/Http/Controllers/Repuve/TagsController.php
index caa46b9..ea6bc00 100644
--- a/app/Http/Controllers/Repuve/TagsController.php
+++ b/app/Http/Controllers/Repuve/TagsController.php
@@ -106,7 +106,7 @@ public function tagStore(Request $request)
                 'box_id' => 'required|integer|exists:boxes,id',
                 'tags' => 'required|array',
                 'tags.*.folio' => 'required|string|max:8',
-                'tags.*.tag_number' => 'required|string|max:32',
+                'tags.*.tag_number' => 'nullable|string|max:32',
             ]);
 
             DB::beginTransaction();
@@ -126,7 +126,7 @@ public function tagStore(Request $request)
                 try {
                     $tag = Tag::create([
                         'folio' => $tagData['folio'],
-                        'tag_number' => $tagData['tag_number'],
+                        'tag_number' => $tagData['tag_number'] ?? null,
                         'box_id' => $request->box_id,
                         'status_id' => $statusAvailable->id,
                         'vehicle_id' => null,