GSTR-1: Outward Supplies Return (Due 11th)

GSTR-1 is the source of truth for the GST system. It feeds your customers' GSTR-2B, which they use to claim ITC. File it wrong or late, your customers lose ITC credit, they call you, you lose the client. Every B2B invoice must be declared invoice-by-invoice.

What goes in GSTR-1 table by table: Table 4A: B2B invoices (every invoice to a GSTIN holder, must have buyer's GSTIN, invoice number, date, taxable value, GST amount). Table 5: B2C interstate invoices above ₹2.5L (state-wise). Table 6: Exports, type of export, shipping bill number if zero-rated. Table 7: B2C supplies (domestic, below ₹2.5L interstate or any intrastate). Table 8: Nil-rated/exempt/non-GST supplies. Table 9/10: Amendments to previous months' invoices. Table 11: Advances received. HSN summary (Table 12): If turnover above ₹5Cr: 6-digit HSN mandatory. ₹1.5Cr to ₹5Cr: 4-digit HSN. Below ₹1.5Cr: 2-digit HSN. From FY 2021-22: all B2B invoices must carry HSN/SAC code. Wrong HSN = input GSTR-2B data for buyer is wrong → buyer's ITC is blocked. Why GSTR-1 accuracy matters for your client: Every B2B invoice you declare in GSTR-1 flows into your buyer's GSTR-2B automatically.