GST APPLICABILITY ON BAD DEBTS RECOVERED

In your case, there was no reversal of tax by way of any credit note. That means you should have already paid the tax though your buyer has not made the payment to you.

If it is the case, why GST is again if you have already shown in the Ruturn during FY 18-19.

In FY 20-21, you receive only payment and do not make any fresh supply.

The problem is for the buyer who has to reverse the ITC after expiry of 180 days of invoice and he will get ITC on subsequent payment. Ref Proviso to Sec.16(2)