GSTR-3B due dates — month-by-month, state-by-state.

1. What GSTR-3B is

GSTR-3B is the summary return with the tax-payment leg — it reports outward and inward supplies in consolidated form, claims ITC, and discharges the net tax liability. Unlike GSTR-1, which is invoice-level, GSTR-3B is an aggregated picture for the period.

3B is where tax is actually paid. Filing it on time is the single most important monthly compliance under GST — late 3B payment carries 18% interest from the original due date, irrespective of how the late filing happened.

2. Monthly vs QRMP

• Monthly: Mandatory for taxpayers with aggregate turnover above ₹5 crore in the previous FY, or anyone who has not opted into QRMP.
• QRMP: Available to taxpayers with aggregate turnover up to ₹5 crore in the previous FY. GSTR-3B is filed quarterly, but tax is paid monthly via PMT-06 challan (due on the 25th).

3. Due date table — monthly filers, FY 2026-27

QRMP — quarterly GSTR-3B, FY 2026-27

PMT-06 monthly tax payment (Months 1 and 2 of each quarter) is due on the 25th of the following month for QRMP filers, irrespective of state group.

4. State groupings for QRMP

The state-group split is administrative — designed to stagger portal load at quarter-end. Confirm your GSTIN's state group against the latest CBIC notification before the first filing of FY 2026-27.

Group A — due 22nd of the month after quarter

Broadly: Chhattisgarh, Madhya Pradesh, Gujarat, Maharashtra, Karnataka, Goa, Kerala, Tamil Nadu, Telangana, Andhra Pradesh, Puducherry, Daman & Diu, Dadra & Nagar Haveli, Andaman & Nicobar, Lakshadweep.

Group B — due 24th of the month after quarter

Broadly: Himachal Pradesh, Punjab, Uttarakhand, Haryana, Rajasthan, Uttar Pradesh, Bihar, Sikkim, Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura, Meghalaya, Assam, West Bengal, Jharkhand, Odisha, Jammu & Kashmir, Ladakh, Delhi, Chandigarh, and other UTs not listed in Group A.

The split historically tracks Western + Southern India (22nd) vs Northern + Eastern + North-Eastern India (24th). Always verify against the current CBIC notification — the list has been adjusted a few times since the QRMP scheme launched.

5. QRMP — fixed-sum vs self-assessment

For Months 1 and 2 of each quarter, QRMP filers choose:

• Fixed-sum method: Pay a 35% challan — 35% of the tax paid in cash in the preceding quarter — if that quarter was filed under QRMP. If the preceding quarter was filed monthly, pay 100% of the tax paid in cash in the last month of that quarter. The fixed amount is pre-populated by the portal in PMT-06.
• Self-assessment method: Compute actual liability for the month from your books and pay that amount.

The full reconciliation happens at the quarter-end GSTR-3B, where you compute actual quarterly liability and pay any differential. The fixed-sum method gives an interest safe-harbour: if you pay the prescribed fixed sum on time and file the quarterly 3B on time, no interest is charged on the differential.

6. Late fees

7. Interest — 18% on unpaid tax

Interest at 18% per annum applies on the net tax liability in GSTR-3B from the original due date until the date of actual payment. The calculation is day-count based on the cash component — ITC offsets do not reduce the principal for interest purposes if the cash leg is delayed.

A higher rate of 24% per annum applies on ITC that was claimed wrongly and utilised. The Government has, by amendment, narrowed the interest base over the years — verify against the current CBIC position before computing for litigation.

8. Sequential filing — GSTR-1 must be filed first

Section 39(10) of the CGST Act prohibits filing GSTR-3B for a period unless GSTR-1 for the same period is already filed. The portal enforces this. In practice this means:

• If you have not finalised invoices for 1, you cannot file 3B — even if 3B tax is ready to pay.
• A late 1 → late 3B → 18% interest on the 3B tax leg.
• For QRMP filers, IFF skipping is fine, but the quarterly 1 must be filed before the quarterly 3B.

File GSTR-1 first, even partially or as a nil return. You can amend in GSTR-1A or next month's amendment table. What you cannot do is unlock 3B without a 1 on file.

For the GSTR-1 cadence and due dates, see the GSTR-1 due date page.

9. DRC-01B and DRC-01C — auto-mismatch notices

• DRC-01B — auto-generated when GSTR-1 outward supplies exceed GSTR-3B outward supplies beyond the tolerance. Reply or pay within 7 days.
• DRC-01C — auto-generated when ITC claimed in GSTR-3B exceeds ITC available in GSTR-2B beyond the tolerance. Reply or pay within 7 days.

Common causes of DRC-01B: amendments in 1 not reflected in 3B, credit notes filed in 1 but not deducted in 3B, exports with IGST included in 1 but missed in 3B Table 3.1(b).

Common causes of DRC-01C: ITC claimed on invoices that the supplier has not yet uploaded, IRN-rejected invoices, duplicated entries.

TatvaBooks prepares GSTR-1 and GSTR-3B and reconciles both against GSTR-2B on a single screen, so a mismatch surfaces while you can still fix it — before you file on the portal, not after a DRC-01B or DRC-01C notice.

10. Frequently asked questions