The two returns every GST-registered business files
If you are registered under GST in India, you need to file two key returns: GSTR-1 (details of outward supplies) and GSTR-3B (summary return with tax payment). Understanding the difference is critical to staying compliant.
| GSTR-1 | GSTR-3B | |
|---|---|---|
| What it is | Invoice-level details of outward supplies (sales) | Self-declared summary of tax liability & ITC |
| Detail level | Per-invoice | Consolidated totals |
| Tax payment | No payment — disclosure only | Yes — net tax is paid here |
| Deadline | 11th of next month (13th for QRMP quarterly) | 20th of next month (varies by state for quarterly) |
| Feeds into | Buyer's GSTR-2B (their ITC) | Your electronic cash/credit ledger |
The numbers you disclose in GSTR-1 must reconcile with what you pay in GSTR-3B. A mismatch is the single most common trigger for a GST notice.
GSTR-1: Your sales details
GSTR-1 contains invoice-level details of all your outward supplies (sales). It includes:
- B2B invoices (with buyer GSTIN) — reported invoice-by-invoice
- B2C invoices (without buyer GSTIN) — reported as consolidated summaries
- Credit notes and debit notes
- Export invoices
- HSN-wise summary of outward supplies
Filing deadline: 11th of the following month (monthly filers) or 13th of the month following the quarter (quarterly filers under QRMP scheme).
GSTR-3B: Your tax summary
GSTR-3B is a self-declared summary return where you report:
- Total outward supplies and tax liability
- Input Tax Credit (ITC) claimed
- Net tax payable (output tax minus ITC)
- Interest and late fees (if applicable)
Filing deadline: 20th of the following month (varies by state for quarterly filers).
Common mistakes
- Mismatch between GSTR-1 and GSTR-3B — the tax liability in GSTR-3B should match the totals in GSTR-1. Mismatches trigger notices.
- Claiming excess ITC — you can only claim ITC that appears in your GSTR-2B (auto-generated from your suppliers' GSTR-1).
- Late filing — attracts interest at 18% p.a. on the tax amount and a late fee of Rs. 50 per day (Rs. 20 for nil returns).
How ReadyBooks.ai helps
ReadyBooks.ai generates GSTR-1 data automatically from your sales invoices and credit notes. The GST dashboard shows your output tax, input tax, and net payable — matching the GSTR-3B format. You can export data in the format required by the GST portal.