GST filing is how you report your sales, purchases, and tax liability to the government through the GST portal, so your Input Tax Credit is recorded correctly and you pay what you owe on time. Every business registered under GST has to file on a fixed schedule, no matter its size, and that includes months with zero transactions.
Missing a deadline isn’t a minor slip. It brings late fees, 18% annual interest on unpaid tax, and if it drags on, it can block your Input Tax Credit or get your registration cancelled. Here’s what GST filing actually involves, which returns apply to you, the current due dates, and how to file without tripping over the common errors.
What Is GST Filing?
GST filing means submitting periodic returns — mainly GSTR-1 (your sales data) and GSTR-3B (your tax summary and payment) — through the GST portal at gst.gov.in. These returns tell the tax department what you sold, what tax you collected, what Input Tax Credit you’re claiming on purchases, and what net tax you owe.
Every GST-registered taxpayer has to file, whether you’re a sole proprietor, a freelancer, a partnership, or a company. There’s no exemption for a quiet month either — a “nil return” still needs to go in by the due date.
Who Needs To File GST Returns?
You need GST registration, and with it the obligation to file, once your turnover crosses these thresholds:
Goods suppliers cross the threshold at ₹40 lakh (₹20 lakh in special category states). Service providers cross it at ₹20 lakh (₹10 lakh in special category states).
Once you’re registered, filing stays compulsory even if your turnover dips below the threshold in a later year. You keep filing until you formally cancel the registration.
The Two Core Returns: GSTR-1 And GSTR-3B
Most of the confusion around GST filing comes down to not knowing what separates these two returns. They do different jobs, and both are mandatory.
GSTR-1: Your Outward Supply Return
GSTR-1 is an invoice-level report of everything you sold in the period — every sale, credit note, and debit note. Your buyers use this data to claim their own Input Tax Credit, so if you get it wrong, it’s their compliance that suffers, not just yours.
Monthly filers, meaning businesses with turnover above ₹5 crore, file by the 11th of the following month. QRMP filers (turnover up to ₹5 crore, opted for quarterly filing) file by the 13th of the month after the quarter ends.
GSTR-3B: Your Summary Return And Tax Payment
GSTR-3B is where you declare your total tax liability, claim ITC, and pay the net tax due. Since 2022 the portal auto-populates most of it from your GSTR-1 and GSTR-2B data, but you’re still on the hook for reviewing those figures before you submit. Once filed, GSTR-3B can’t be revised.
Monthly filers are due on the 20th of the following month. QRMP filers are due on the 22nd or 24th of the month after the quarter ends, depending on which state category you fall into.
One thing that trips people up: GSTR-1 has to be filed before GSTR-3B for the same period. The portal enforces this order, so you can’t file out of sequence even by accident.
GST Filing Due Dates At A Glance (FY 2026-27)
| Return | Filing frequency | Due date |
|---|---|---|
| GSTR-1 | Monthly | 11th of the following month |
| GSTR-1 (IFF) | QRMP, months 1 & 2 of quarter | 13th of the following month |
| GSTR-1 | QRMP, quarterly | 13th after quarter end |
| GSTR-3B | Monthly | 20th of the following month |
| GSTR-3B | QRMP | 22nd or 24th after quarter end (state-dependent) |
| PMT-06 (tax payment) | QRMP | 25th of the following month |
| GSTR-9 (Annual Return) | Annually | 31st December after FY end |
| GSTR-9C (Reconciliation) | Annually, turnover above ₹5 crore | 31st December after FY end |
Due dates do shift occasionally, usually when the CBIC issues an extension notification after a portal outage. Don’t assume an extension covers you just because you heard about one — check the portal directly.
Should You File Monthly Or Opt For QRMP?
If your aggregate annual turnover is up to ₹5 crore, you can opt into the QRMP scheme (Quarterly Return Monthly Payment). It cuts your GSTR-1 and GSTR-3B filing down to once a quarter, while you keep depositing tax monthly through Form PMT-06.
QRMP tends to make sense when your transaction volume is low enough that monthly filing feels like busywork, or when you’d rather have fewer compliance touchpoints without losing the discipline of paying tax every month.
It’s less of a fit if you have credit-sensitive B2B buyers who need to see their ITC every month. In that case, use the Invoice Furnishing Facility (IFF) in months 1 and 2 of the quarter instead of skipping straight to quarterly filing.
Step-By-Step: How To File GST Returns
Start by reconciling your records — match your sales register, purchase register, and GSTR-2B (your ITC statement) before you go anywhere near the portal. Skipping this step is where most errors start.
Log in to the GST portal at gst.gov.in with your GSTIN credentials, then file GSTR-1 first. Go to Services → Returns → Returns Dashboard, select the period, and upload or confirm your invoice-wise sales data.
Next, download GSTR-2B for the period so you can verify your eligible Input Tax Credit before you move on. Once that’s checked, prepare GSTR-3B. The portal will auto-populate outward supply and ITC figures from your GSTR-1 and GSTR-2B, but review every table anyway, especially the auto-populated ones — most of those fields aren’t editable under current rules, so catching an error before you submit matters more than it used to.
Pay the net tax liability shown, then submit and file using your digital signature or EVC. Hold on to your filed acknowledgments and payment challans; you’ll need them at year-end when GSTR-9 comes around.
GST Late Fees And Penalties
| Return | Late fee |
|---|---|
| GSTR-1 (regular) | ₹50/day (₹25 CGST + ₹25 SGST) |
| GSTR-1 (nil) | ₹20/day (₹10 + ₹10) |
| GSTR-3B (turnover up to ₹1.5 crore) | ₹50/day, capped at ₹5,000 per return |
| GSTR-3B (nil) | ₹20/day, capped at ₹500 |
| Interest on unpaid tax | 18% per annum, calculated from the due date |
These add up faster than most people expect. A ten-day delay on a fairly modest tax liability can cross ₹1,000 once you combine the late fee and interest, and if late filing becomes a pattern over a year, you’re looking at thousands of rupees gone to penalties alone, before you even factor in the compliance risk.
Common GST Filing Mistakes To Avoid
Misclassifying B2B sales as B2C blocks your buyer’s ITC claim and creates reconciliation headaches later. Wrong or missing HSN/SAC codes cause mismatches that surface during the annual return. Forgetting to report credit notes overstates your tax liability. Filing GSTR-3B without reconciling GSTR-2B first is one of the more common reasons businesses end up with ITC-related notices. And assuming a due date extension applies to you, without checking the actual CBIC notification, is a mistake worth double-checking every single time.
FAQs
Yes. A nil return still has to be filed by the due date, for every registered taxpayer, even in months with no transactions.
GSTR-1 reports what you sold, invoice by invoice. GSTR-3B is a summary return where you declare total tax liability, claim Input Tax Credit, and pay the net tax due. Both are mandatory, and they have to be filed in sequence, GSTR-1 first.
No. Once you submit it, GSTR-3B can’t be revised for that tax period. Corrections happen through subsequent periods’ returns instead.
You’ll be charged a late fee, ₹50/day for regular returns or ₹20/day for nil returns, plus 18% annual interest on any unpaid tax, calculated from the original due date.
Businesses with an aggregate annual turnover up to ₹5 crore in the previous financial year can opt for QRMP, filing GSTR-1 and GSTR-3B quarterly while still paying tax monthly.
Three years past the original due date. After that, the tax period is permanently blocked on the portal and can’t be filed at all.
Filing accurately every month protects your Input Tax Credit, keeps your compliance rating healthy, and saves you from late fees and interest compounding quietly in the background. If your filings have fallen behind, or you just want a second set of eyes on your monthly compliance, talk to our team for a review.
