What GSTR-1 Contains
GSTR-1 is a comprehensive invoice-level return. It requires reporting of all B2B invoices with the buyer's GSTIN, invoice number, date, taxable value, and tax amounts split into IGST, CGST, and SGST. B2C inter-state invoices above ₹2.5 lakh must be reported individually; smaller B2C transactions are reported as a consolidated state-wise summary. Exports (with and without payment of IGST), credit notes, debit notes, and advances received for future supplies must also be reported. From FY 2021-22, HSN-wise summary (Table 12) is mandatory for all taxpayers.
Monthly vs QRMP Filers
Taxpayers with aggregate annual turnover up to ₹5 crore can opt for the QRMP (Quarterly Return Monthly Payment) scheme. Under QRMP, GSTR-1 is filed quarterly (due 13th of the month after quarter end), but tax is paid monthly via a fixed sum or self-assessed challan. QRMP filers can use the Invoice Furnishing Facility (IFF) in months 1 and 2 of the quarter to upload B2B invoices so buyers can claim ITC without waiting for the quarterly GSTR-1. Taxpayers above ₹5 crore turnover must file GSTR-1 monthly.
Impact on Buyers' ITC
Every invoice you report in GSTR-1 flows into your buyer's GSTR-2B on the 14th of the following month. GSTR-2B is the static ITC statement that buyers use to claim input tax credit in their GSTR-3B. If you file GSTR-1 late or with errors, your buyers' ITC is blocked or reduced. Under Rule 36(4), buyers can only claim ITC to the extent it appears in GSTR-2B — there is no provisional ITC allowance since January 2022. Accurate and timely GSTR-1 filing is therefore critical for your business relationships.
Amendments and Corrections
Errors in GSTR-1 can be corrected in the next month's GSTR-1 using amendment tables (Table 9A for B2B amendments, Table 9B for credit/debit note amendments). You cannot directly edit a filed GSTR-1. Amendments must be made within the time limit — by October 31 of the following financial year or the date of filing the annual return (GSTR-9), whichever is earlier.