Gstr1 calrification

If you're sold goods or services then you may report in3B and gstr1

As per law supplies of the month to be uploaded. There is no link to payment. 

You have to upload all invoices in next month return and pay gst for same.

You have to upload all the invoices, if the party is not willing to pay not at all, you can issue credit note and reduce output tax liability.

As per Section 37 & 39 (both of CGST Act) , you are required to report all your outward supply in GSTR 1 & file your input output tax in your corresponding 3B .

Dear David :
The Supplier cannot issue the credit for Non payment by Receptient. yes if Supplier takes the goods return for the same then can Reduce his output tax liability.

As per Provisio u/s 16 of CGST Act , if Recepeint who fails to pay Supplier within 180 days from date of invoice,he is liable to reverse the ITC on same with interest.

Yes the Supplier can write-off the outstanding by providing bad debt provision but even then Supplier cannot reduce its Output Tax Liability as bad debts is not cover under GST.

@ pankaj Sir, Thank you