Rohit's GSTIN is live. He paid his first GST last week. Now his CA friend says, "Great. Now file the three returns." Three?! He thought paying was the filing.
Spoiler: payment ≠ filing. Filing three returns ≠ filing one. Here's what each one does.
- GSTR-1 — your sales return. Due 11th of next month (13th if quarterly QRMP).
- GSTR-3B — your summary + tax payment confirmation. Due 20th of next month.
- GSTR-9 — annual consolidation. Due 31 December of next FY. Mandatory if turnover > ₹2 cr.
- Skip any one = late fees + interest + your buyers' Input Tax Credit gets blocked.
The big mental model: it's a relay race
Forget "three forms". Think of it as one continuous handover:
👉 Step 1 — your sales invoices get uploaded as GSTR-1 by the 11th.
👉 Step 2 — those invoices auto-flow into your buyer's GSTR-2B on the 14th.
👉 Step 3 — by the 20th, you file GSTR-3B to declare totals and pay the net GST.
👉 Step 4 — by 31 December next year, GSTR-9 rolls up the whole year and reconciles with your books.
Each one feeds the next. Skip one and the chain breaks somewhere.
GSTR-1 — your sales return
This is where you tell the government "here's everything I sold this month" — invoice by invoice for B2B sales, and as a summary for B2C.
What goes in
- B2B invoices — full details (invoice number, date, buyer GSTIN, taxable value, tax)
- B2C large (above ₹2.5L inter-state) — invoice details
- B2C small — state-wise + rate-wise summary
- Credit notes / debit notes
- Exports — with shipping bill details
- HSN-wise summary of outward supplies
Your GSTR-1 entries flow into your buyer's GSTR-2B. If you file late or skip an invoice, your buyer can't claim ITC on that purchase. They will chase you. If you do it twice, they'll switch vendors. GSTR-1 isn't private homework — it's a public hand-off.
GSTR-3B — settle up + pay
This is the "reconcile and pay" return. Filed by the 20th of the next month (24th for some states in QRMP). It declares:
👉 Total outward supplies (from your GSTR-1)
👉 ITC claimed (from your GSTR-2B + adjustments)
👉 Net tax liability after offsetting
👉 Tax paid (from the challan you generated)
Most of this is auto-populated now from your GSTR-1 + GSTR-2B. Your job is to verify, not blindly accept.
Monthly vs Quarterly — pick your rhythm
Monthly
Turnover > ₹5 cr
12 GSTR-1s + 12 GSTR-3Bs per year. Mandatory above ₹5 cr.
QRMP
Turnover ≤ ₹5 cr
Pay tax monthly via PMT-06; file GSTR-1 + 3B quarterly. Use IFF in months 1 & 2 of quarter so buyers get ITC sooner.
GSTR-9 — the year-end roll-up
Once a year, you file GSTR-9 — a consolidated picture of everything from your 12 monthly GSTR-1s and GSTR-3Bs, reconciled with your books.
👉 Mandatory — if turnover > ₹2 cr
👉 Optional — turnover ≤ ₹2 cr (most small businesses skip)
👉 GSTR-9C (Reconciliation Statement) — additionally required if turnover > ₹5 cr (self-certified now, no CA cert)
Due 31 December of the next financial year. (FY 25-26 → due 31 Dec 2026.)
The deadline calendar
For QRMP filers: GSTR-1 due 13th (quarterly). Use IFF on 13th of months 1 & 2 of the quarter.
System pulls all vendor GSTR-1 uploads. Your ITC eligibility is locked here.
Monthly. QRMP filers: 22nd or 24th depending on state. PMT-06 by 25th for QRMP months 1 & 2.
Annual return for previous FY. Self-certified reconciliation if applicable.
How late filing hurts
Nil returns still attract ₹20/day late fee. Even if you billed zero this month — file nil GSTR-1 and nil GSTR-3B by their deadlines.
Most small businesses don't lose money to GST — they lose it to GST late fees. Three calendar reminders solve the entire problem.
The 11-20 monthly rhythm
If you do nothing else, just remember this two-date pattern:
👉 By the 11th: GSTR-1 filed (or IFF uploaded for QRMP).
👉 By the 18th: GST paid via challan (3 days buffer before deadline).
👉 By the 20th: GSTR-3B filed.
Set 3 phone alerts. Done forever.
Quick answers
Yes. Even nil GSTR-1 and nil GSTR-3B must be filed by their deadlines. Late nil filings still attract ₹20/day fee.
You can amend in a later month's GSTR-1 (Tables 9A, 9B, 9C for amendments). Best done in the very next month. Once GSTR-9 for the year is filed, amendments to that year are locked.
Quarterly Return Monthly Payment. For taxpayers with turnover ≤ ₹5 cr — file GSTR-1 + GSTR-3B quarterly but pay tax monthly via PMT-06 (25th). Use IFF in months 1 & 2 so your buyers get ITC sooner.
Filing GSTR-9 is optional below ₹2 cr. Filing it anyway is a clean year-end practice — it acts as your own reconciliation checkpoint.
Check your GSTR-1 — did you upload the invoice with the correct buyer GSTIN? If not, amend in this month's GSTR-1 (Table 9A). Their 2B will reflect in next month.
When you might want help
Filing nil returns is DIY. Where it gets messy: reconciling GSTR-1 with sales register monthly, chasing vendors whose GSTR-1 is late so your GSTR-2B stays clean, handling amendments and credit notes correctly, and the GSTR-9 / 9C year-end reconciliation that turns 12 months of data into one document.
Want monthly GST handled for you?
End-to-end filing — GSTR-1, 3B, 9 + reconciliation + late-vendor chasing — for a fixed monthly fee.