GSTR-1 and GSTR-3B are the two returns most regular GST taxpayers file — and they do very different jobs. One reports your sales in detail; the other is where you actually pay. Here is how they differ and why they must agree.
GSTR-1 — the detail of your sales
GSTR-1 is a statement of your outward supplies (sales). It reports your sales invoice by invoice — B2B invoices individually, B2C sales in summary, plus credit and debit notes and exports. Crucially, no tax is paid in GSTR-1; it is disclosure. The detail you file here also feeds your buyers' input tax credit.
GSTR-3B — the summary where you pay
GSTR-3B is a summary return. You report total outward supplies, claim your input tax credit (guided by the auto-drafted GSTR-2B), arrive at a net liability, and pay the tax. It is the return that settles what you owe for the period.
GSTR-1 vs GSTR-3B at a glance
| GSTR-1 | GSTR-3B | |
|---|---|---|
| Purpose | Report outward supplies (sales) | Summarise & pay net tax |
| Level of detail | Invoice-wise | Summary totals |
| Is tax paid here? | No | Yes |
| Input tax credit | Not covered | Claimed here |
| Frequency | Monthly, or quarterly under QRMP | Monthly, or quarterly under QRMP |
| Typical due date | Around the 11th of the next month* | Around the 20th (staggered for QRMP)* |
Why they have to reconcile
The outward supplies you summarise in GSTR-3B should match the invoice-level sales you reported in GSTR-1. When they drift apart, it is a common trigger for GST notices. The reliable fix is upstream: keep one clean set of books so both returns are derived from the same source data rather than assembled separately.
Make reconciliation a non-event
If every GST invoice posts into your books as you raise it, your GSTR-1 detail and your GSTR-3B summary come from the same numbers — so they agree by default. That is the whole idea behind keeping billing and accounting in one place.