GSTR 3B & GSTR-1

No time limit

You need to file all pending GSTR 3B return with intetest and late fees

As per the Provision of Section 29(2) clause (c) of the CGST Act 2017, If a person fails to furnish GST Returns for a continuous period of "Six Months" , then his Registration is liable to be cancelled by the Proper Officer on sou-motto basis.

Moreover a Notice is issued by the department to Non filers of Return in FORM GSTR-3A in accordance with the Provision of Section 46 of the CGST Act 2017 read with Rule 68 of the CGST Rules 2017, which requires them to file all the pending GST Returns with the applicable Late Fees ( U/s 47 ) and Interest ( U/s 50 ) within 15 days from the date of receiving the Notice in FORM GSTR-3A.

As far as the time limit to issue Notice is concerned, there is no such time limit mentioned under the GST Law. It is issued by the department as per their convenience ( any time ).

Since in your case no Notice had been issued yet to your client regarding filing of GSTR-3B, I would suggest you to file all your pending GSTR-3B ( with the applicable late fees and Interest ) and clear all liabilities with the Department inorder to avoid any type of litigation in the future.

Regards,
Shivam RC.

At present you are requested to contact the concerned gst authorities to clear all liabilities to avoid all kinds of litigations.

Why GSTR 3B return not filed by your client?

Yes agree with Mr. Shivam RC , it's better to file all your GSTR 3B , before you got any notice for the same.