Missing invoices will attract interest

S.RAMA (BOOK KEEPING & TAX CONSULTANT)   (88 Points)

04 January 2021  
4 invoices of may 2020 was missed to be added while filing gstr3b gstr1 of may2020. can it be added now and whether interest is levied on tax amount of missing tax invoices . how much % and how to disclose in gstr1.pls guide.tnx