diff --git a/form 16 build (6 march).zip b/form 16 build (6 march).zip
deleted file mode 100644
index 9182b8e..0000000
Binary files a/form 16 build (6 march).zip and /dev/null differ
diff --git a/src/services/form16.service.ts b/src/services/form16.service.ts
index eb6230d..d265a76 100644
--- a/src/services/form16.service.ts
+++ b/src/services/form16.service.ts
@@ -745,6 +745,13 @@ async function renameForm16SubmissionPdfAfterCreditNote(params: {
   oldRelativePath: string;
 }): Promise<void> {
   const { submissionId, requestId, oldRelativePath } = params;
+  logger.info('[Form16] PDF rename flow start', {
+    submissionId,
+    requestId,
+    oldRelativePath,
+    nodeEnv: process.env.NODE_ENV,
+    gcpBucket: process.env.GCP_BUCKET_NAME || null,
+  });
   const oldPathNorm = String(oldRelativePath || '').replace(/\\/g, '/').trim();
   if (!oldPathNorm || oldPathNorm.includes('..') || !oldPathNorm.startsWith('requests/')) {
     logger.warn('[Form16] Skip PDF rename: invalid storage path', { oldPathNorm });
@@ -752,16 +759,39 @@ async function renameForm16SubmissionPdfAfterCreditNote(params: {
   }
 
   const sub = await Form16aSubmission.findByPk(submissionId);
-  if (!sub) return;
+  if (!sub) {
+    logger.warn('[Form16] Skip PDF rename: submission not found', { submissionId, requestId });
+    return;
+  }
 
   const newFileName = buildForm16CreditNoteSuccessPdfFileName(sub);
+  logger.info('[Form16] PDF rename target name computed', {
+    submissionId,
+    requestId,
+    newFileName,
+    tanNumber: (sub as any).tanNumber || null,
+    financialYear: (sub as any).financialYear || null,
+    quarter: (sub as any).quarter || null,
+    form16aNumber: (sub as any).form16aNumber || null,
+  });
 
   try {
     const result = await gcsStorageService.renameRequestDocumentFile({
       oldRelativePath: oldPathNorm,
       newFileName,
     });
+    logger.info('[Form16] Storage rename success', {
+      submissionId,
+      requestId,
+      oldPathNorm,
+      renamedFilePath: result.filePath,
+      renamedStorageUrlPrefix: String(result.storageUrl || '').slice(0, 120),
+    });
     await sub.update({ documentUrl: result.storageUrl });
+    logger.info('[Form16] Submission documentUrl updated after rename', {
+      submissionId,
+      requestId,
+    });
 
     const doc = await Document.findOne({
       where: { requestId, filePath: oldPathNorm },
@@ -776,6 +806,13 @@ async function renameForm16SubmissionPdfAfterCreditNote(params: {
         filePath: fp,
         storageUrl: su,
       });
+      logger.info('[Form16] Document metadata updated after rename', {
+        requestId,
+        submissionId,
+        documentId: (doc as any).id || null,
+        oldPathNorm,
+        newPath: fp,
+      });
     } else {
       logger.warn('[Form16] PDF renamed; documents row not found for path', { requestId, oldPathNorm });
     }
@@ -1331,6 +1368,12 @@ export async function createSubmission(
     );
     // When credit note is issued (completed), set workflow status to CLOSED so the request appears on Closed requests page
     if (validationStatus === 'success' && creditNoteNumber) {
+      logger.info('[Form16] Success path reached; triggering PDF rename', {
+        requestId,
+        submissionId: submission.id,
+        creditNoteNumber,
+        uploadFilePath,
+      });
       const workflow = await WorkflowRequest.findOne({ where: { requestId }, attributes: ['requestId', 'status'] });
       if (workflow && (workflow as any).status !== WorkflowStatus.CLOSED) {
         await workflow.update({ status: WorkflowStatus.CLOSED });
@@ -1341,6 +1384,17 @@ export async function createSubmission(
         requestId,
         oldRelativePath: uploadFilePath.replace(/\\/g, '/'),
       });
+      logger.info('[Form16] PDF rename call completed', {
+        requestId,
+        submissionId: submission.id,
+      });
+    } else {
+      logger.info('[Form16] PDF rename not triggered (submission not successful)', {
+        requestId,
+        submissionId: submission.id,
+        validationStatus,
+        creditNoteNumber: creditNoteNumber || null,
+      });
     }
   } catch (err: any) {
     logger.error(
diff --git a/src/services/gcsStorage.service.ts b/src/services/gcsStorage.service.ts
index bd4e71b..e694767 100644
--- a/src/services/gcsStorage.service.ts
+++ b/src/services/gcsStorage.service.ts
@@ -355,6 +355,14 @@ class GCSStorageService {
   }): Promise<{ storageUrl: string; filePath: string; fileName: string }> {
     const { oldRelativePath } = options;
     let newFileName = path.basename(String(options.newFileName || '').trim());
+    logger.info('[GCS] renameRequestDocumentFile called', {
+      oldRelativePath,
+      requestedNewFileName: options.newFileName,
+      sanitizedNewFileName: newFileName,
+      nodeEnv: process.env.NODE_ENV,
+      bucket: this.bucketName || null,
+      useGoogleSecretManager: process.env.USE_GOOGLE_SECRET_MANAGER || null,
+    });
     if (!newFileName || newFileName === '.' || newFileName === '..') {
       throw new Error('Invalid new file name');
     }
@@ -367,6 +375,7 @@ class GCSStorageService {
     const newRelativePath = `${dir}/${newFileName}`;
 
     if (!this.isConfigured()) {
+      logger.info('[GCS] renameRequestDocumentFile using local storage mode');
       const fullOld = path.join(UPLOAD_DIR, ...oldNorm.split('/').filter(Boolean));
       const fullNew = path.join(UPLOAD_DIR, ...newRelativePath.split('/').filter(Boolean));
       if (!fs.existsSync(fullOld)) {
@@ -387,12 +396,19 @@ class GCSStorageService {
       const bucket = this.storage.bucket(this.bucketName);
       const oldFile = bucket.file(oldNorm);
       const [exists] = await oldFile.exists();
+      logger.info('[GCS] renameRequestDocumentFile GCS existence check', {
+        oldNorm,
+        exists,
+        newRelativePath,
+      });
       if (!exists) {
         throw new Error(`GCS file not found: ${oldNorm}`);
       }
       const newFile = bucket.file(newRelativePath);
       await oldFile.copy(newFile);
+      logger.info('[GCS] renameRequestDocumentFile copy success', { from: oldNorm, to: newRelativePath });
       await oldFile.delete();
+      logger.info('[GCS] renameRequestDocumentFile delete old success', { oldNorm });
 
       let publicUrl: string;
       try {