GST · ITC · Reconciliation · GSTR-2B · Rule 36(4)
Your GSTR-3B claim and GSTR-2B do not match. Here is what that means — and the 30-day windows around it.
ITC mismatches are the most common reason GST notices arrive. The statute gives you specific windows to fix them — and specific consequences when you do not.
The four issues
Where this area actually goes wrong.
Each of the four pillars below is statute-cited — the section, the form, and the consequence. No vague claims.
GSTR-2B vs GSTR-2A — what each statement is
GSTR-2A is the dynamic, transaction-level statement of input tax credit reflected from your suppliers' GSTR-1/5/6/9 returns — it updates continuously as suppliers file or amend. GSTR-2B is the static monthly ITC statement introduced from August 2020 — the portal freezes your ITC position for each month in a single PDF you can download. Both pull from the same underlying supplier data; 2B is what the department compares against your GSTR-3B claim. A mismatch between the two is the single biggest audit trigger under GST.
2B static since Aug 2020 · 2A dynamic · both portal auto-generated
ITC eligibility — s.16(2), s.17(5), s.16(4)
Section 16(2) of the CGST Act makes ITC available only when every condition is met: you possess the tax invoice (a), the goods or services are received (b), tax has actually been paid to the government by the supplier (c), and you have paid the supplier within 180 days (d) — otherwise the credit is reversed with interest. Section 17(5) blocks credit outright for listed items — motor vehicles (except specified cases), food and beverages, personal consumption, and works contract services on immovable property except as specified. Section 16(4) is the time bar: credit must be claimed in GSTR-3B by the due date of the September return following the financial year, or the annual return date, whichever is earlier.
s.16(2)(a)–(d) · s.17(5) blocked credit · s.16(4) September time bar
The matching rule — Rule 36(4)
From 1 January 2022, Rule 36(4) of the CGST Rules caps the ITC claimed in GSTR-3B at the amount reflected in your GSTR-2B — the earlier tolerance of 20% (later 10%) of unmatched credit was removed. Claim more than 2B shows and the system flags the difference, which surfaces as an ASMT-10 intimation of discrepancy under Rule 99 and can escalate to a DRC-01C/DRC-01 demand. Your purchase register must therefore reconcile to 2B before you file 3B — not after.
Rule 36(4) 100% matching · no tolerance since Jan 2022 · ASMT-10 → DRC-01
Four-way reconciliation — the defence document
A proper reconciliation runs four comparisons: purchase register → GSTR-2B → GSTR-3B claim → GSTR-2A. It surfaces missing or wrong supplier invoices, purchases from unregistered vendors (no ITC), reverse-charge transactions under s.9(3)/s.9(4), ISD distributions under s.20, credit notes, and blocked credit under s.17(5). The output — a dated mismatch register with a reason against every difference — is the document that answers an ASMT-10, DRC-01A or departmental scrutiny, and it is the document most businesses do not have.
books vs 2B vs 3B vs 2A · RCM & ISD · mismatch register as defence
The GST return calendar — every filing date, with its provision
Every GST return date on one table — each row read from the repo deadline fixture and the on-disk CGST Act/Rules text, with the provision named. Rows marked VERIFY depend on a CBIC notification that is not yet filed in kb-sources; the statutory window is stated from the Act text.
| Filing | Due | Who / when it applies | If missed | Source |
|---|---|---|---|---|
| GSTR-1 — outward supplies details (monthly, regular scheme) | 11th of the month following the tax period | Every registered person furnishing monthly outward-supply details under s.37(1) — the Act text sets the window: "on or before the tenth day of the month succeeding the said tax period"; the calendar day (11th) is the prescribed form date configured in the repo deadline fixture (id GSTR-1, due_rule day 11, month_offset 1) [VERIFY against the current CBIC form-date notification before relying on a specific month] | Late fee under s.47(1): one hundred rupees per day of failure, capped at five thousand rupees — "Any registered person who fails to furnish the details of outward supplies required under section 37 … shall pay a late fee of one hundred rupees for every day" | apps/harunraaj-com/lib/deadlines/legacy-rules.fixture.jsonRepo deadline fixture, id GSTR-1 (due_rule day 11, month_offset 1); day-window statute: CGST Act s.37(1) (kb-sources/cgst/cgst-act-2017-consolidated.pdftotext.e2b3482c1b7c.txt, L3842 "on or before the tenth day of the month succeeding the said tax period"); late fee s.47(1) (same file, L4291). |
| GSTR-1 — outward supplies details (QRMP quarterly filers) | 13th of the month following the quarter | Quarterly Return, Monthly Payment (QRMP) scheme filers — scheme election under s.39(1) proviso ("the Government may … notify certain class of registered persons who shall furnish a return for every quarter"); quarter date configured in the repo fixture (id GSTR-1-QRMP, due_rule day 13, month_offset 1) [VERIFY against the current CBIC QRMP notification before relying on a specific quarter] | Late fee under s.47(1) as for monthly GSTR-1: one hundred rupees per day, capped at five thousand rupees | apps/harunraaj-com/lib/deadlines/legacy-rules.fixture.jsonRepo deadline fixture, id GSTR-1-QRMP (due_rule day 13, month_offset 1); quarter-return power: CGST Act s.39(1) (kb-sources/cgst/cgst-act-2017-consolidated.pdftotext.e2b3482c1b7c.txt, L4009) with the quarter-return proviso (same file, L4023 "registered persons who shall furnish a return for every quarter"); late fee s.47(1) (same file, L4291). |
| GSTR-3B — monthly summary return (regular scheme) | 20th of the month following the tax period | Registered persons furnishing the monthly inward/outward summary return under s.39(1) — the Act leaves form and time to prescription ("within such time … as may be prescribed"); the 20th is the prescribed date configured in the repo deadline fixture (id GSTR-3B, due_rule day 20, month_offset 1) [VERIFY against the current CBIC GSTR-3B date notification before relying on a specific month] | Late fee under s.47(1): one hundred rupees per day of failure to furnish the s.39 return, capped at five thousand rupees | apps/harunraaj-com/lib/deadlines/legacy-rules.fixture.jsonRepo deadline fixture, id GSTR-3B (due_rule day 20, month_offset 1); monthly-return obligation + delegated timing: CGST Act s.39(1) (kb-sources/cgst/cgst-act-2017-consolidated.pdftotext.e2b3482c1b7c.txt, L4009); late fee s.47(1) (same file, L4291). |
| GSTR-3B — quarterly summary return (QRMP scheme) | 22nd (Category X states) / 24th (Category Y states) of the month following the quarter | QRMP filers; the state-category split (X/Y) is the prescribed date structure configured in the repo deadline fixture (id GSTR-3B-QRMP, due_rule day_category_x 22, day_category_y 24, month_offset 1) [VERIFY against the current CBIC QRMP notification — the category lists are notification content and are not on disk] | Late fee under s.47(1) as for monthly GSTR-3B: one hundred rupees per day, capped at five thousand rupees | apps/harunraaj-com/lib/deadlines/legacy-rules.fixture.jsonRepo deadline fixture, id GSTR-3B-QRMP (day_category_x 22 / day_category_y 24); quarter-return power: CGST Act s.39(1) (kb-sources/cgst/cgst-act-2017-consolidated.pdftotext.e2b3482c1b7c.txt, L4009) with the quarter-return proviso (same file, L4023 "registered persons who shall furnish a return for every quarter"); late fee s.47(1) (same file, L4291). |
| GSTR-9 — annual return | Before 31 December following the end of the financial year | "Every registered person" other than an ISD, a person paying tax under s.51/s.52, a casual taxable person and a non-resident taxable person — s.44(1): "before the thirty first day of December following the end of such financial year"; Rule 80(1) prescribes the form (FORM GSTR-9). The repo fixture configures the same date for turnover above twenty lakh (id GSTR-9, due_rule day 31, month 12, turnover_gt 20000000) | Late fee under s.47(2): one hundred rupees per day, capped at a quarter per cent of turnover in the State or Union territory — "Any registered person who fails to furnish the return required under section 44 by the due date shall be liable to pay a late fee of one hundred rupees for every day" | apps/harunraaj-com/lib/deadlines/legacy-rules.fixture.jsonRepo deadline fixture, id GSTR-9; date + scope statute: CGST Act s.44(1) (kb-sources/cgst/cgst-act-2017-consolidated.pdftotext.e2b3482c1b7c.txt, L4695 "before the thirty first day of December following the end of such financial year", exclusions L4224); form: CGST Rules Rule 80(1) (kb-sources/cgst/cgst-rules-2017-part-a.pdftotext.d03f5bcfe3b2.txt, L3924); late fee s.47(2) (Act text, L4298-4300). |
| GSTR-9C — reconciliation statement (audit) | With the annual return — before 31 December following the end of the financial year | "Every registered person whose aggregate turnover during a financial year exceeds two crore rupees shall get his accounts audited … and he shall furnish a copy of audited annual accounts and a reconciliation statement … in FORM GSTR-9C" — Rule 80(3); the repo fixture configures the same 31 December date for turnover above fifty lakh (id GSTR-9C, due_rule day 31, month 12, turnover_gt 50000000) [VERIFY the fixture's fifty-lakh gating against Rule 80(3)'s two-crore audit threshold — the fixtures carry a lower commercial cutoff] | Late fee exposure under s.47(2) as for GSTR-9, plus the audit-furnishing obligation itself sits in Rule 80(3) read with s.35(5) | apps/harunraaj-com/lib/deadlines/legacy-rules.fixture.jsonRepo deadline fixture, id GSTR-9C; form + two-crore audit threshold: CGST Rules Rule 80(3) (kb-sources/cgst/cgst-rules-2017-part-a.pdftotext.d03f5bcfe3b2.txt, L3936); annual-return date anchor: CGST Act s.44(1) (Act text, L4695); late fee s.47(2) (Act text, L4298-4300). |
| TDS return under GST (s.51 deductors) | Within ten days after the end of the month in which the deduction was made | Persons required to deduct tax at source under s.51 (Government and notified entities): s.39(3) — "within ten days after the end of the month in which such deduction is made, in such manner as may be prescribed"; the form is GSTR-7 (prescribed by rule, not on disk) | Late fee under s.47(1): one hundred rupees per day, capped at five thousand rupees (s.47(1) expressly covers "returns required under section 39") | kb-sources/cgst/cgst-act-2017-consolidated.pdftotext.e2b3482c1b7c.txtCGST Act s.39(3) (L4599 "within ten days after the end of the month in which such deduction is made"); TCS-parallel wording for s.52 at L4668; late fee s.47(1) (L4291). |
Scope: returns under the CGST Act, 2017 as consolidated on disk (kb-sources/cgst/, fetched 2026-09-19). Registration-certification and e-invoice dates are out of this table's scope. Extension notifications (Covid-era GSTR-3B waivers, for example) are period-specific and are deliberately not stated here — confirm the current month's date with us before filing.
The honest angle
Why ITC mismatches become demands
The mismatch itself is usually fixable. What turns it into a demand is believing the portal is wrong without a document trail — or missing the statutory windows to correct it.
No invoice, no credit
Purchase from an unregistered vendor means zero ITC — you cannot manufacture credit. Since October 2021, s.9(4) reverse charge on all unregistered purchases is narrowed to specified goods; the practical rule is simpler: get the invoice and the supplier's GSTR-1 filed.
The 180-day payment rule bites when you are cash-strapped
s.16(2)(d) reverses credit with interest if you do not pay the supplier within 180 days — and businesses deferring supplier payments are exactly the ones carrying the credit.
September is a hard deadline
s.16(4) bars credit not claimed by the due date of the September return following the year. A credit found in October is a credit lost — no discretion, no appeal on merits.
2B is the ceiling
Rule 36(4) gives the department the arithmetic. Claiming against a purchase register the portal does not yet reflect is an invitation to ASMT-10 — reply within 30 days or it hardens into a demand.
Our engagement
Five tracks for a clean ITC position.
GSTR-2B vs books reconciliation
Four-way match (purchase register, 2B, 3B claim, 2A) with a dated mismatch register and a reason against every difference.
Monthly
Supplier follow-up and corrections
Identify suppliers missing from 2B, drive their GSTR-1 filing or amendment within the statutory correction window, and re-claim credit in the month it appears.
Monthly
RCM and ISD review
Reverse-charge entries under s.9(3)/s.9(4) and Input Service Distributor allocation under s.20 — the two credit lines most often missed or double-counted.
Monthly / quarterly
Blocked credit and 180-day tracking
s.17(5) blocked items review and a 180-day payment tracker so s.16(2)(d) reversals never surprise you.
Monthly
ASMT-10 / DRC-01C response
Reply within the 30-day window with the reconciliation register as support — before the intimation hardens into a demand.
As needed
FAQs
Five questions every reconciliation raises.
GSTR-2B shows less ITC than my purchase register. Can I still claim the full amount in GSTR-3B?
No. Under Rule 36(4) of the CGST Rules, from 1 January 2022 the ITC claimed in GSTR-3B cannot exceed the amount reflected in GSTR-2B — the earlier 20%/10% tolerance was removed. Claiming more creates a discrepancy that the department sees as an ASMT-10 intimation under Rule 99. The correct sequence: identify which suppliers are missing from 2B, get them to file or amend their GSTR-1 within the correction window, and claim the credit in the month it appears in your 2B — within the s.16(4) September time bar.
I did not pay my supplier within 180 days. What happens to my ITC?
Under s.16(2)(d) of the CGST Act, if you do not pay the supplier within 180 days of the invoice, the credit you took must be reversed — added back to your output tax liability — along with interest under s.50 for the period the credit was held. The good news: the credit is not lost permanently. When you subsequently pay the supplier, you can re-claim the ITC. The practical fix is a payment tracker so reversals with interest never come as a surprise at year-end.
Can I claim ITC for last financial year's purchases in June this year?
Only if you claim it by the due date of the September return following that financial year — s.16(4) of the CGST Act. For FY 2025-26, that means claiming in a GSTR-3B filed by the September 2026 due date (20 October 2026 for monthly filers), or by the annual return date, whichever is earlier. Credit discovered after that is barred — the department has no discretion to allow it. A July/August reconciliation before the September return is the last reliable window.
My supplier's GSTIN is cancelled, but he issued an invoice with his old GSTIN. Can I take the credit?
No — and claiming it is where the exposure starts. ITC requires under s.16(2)(c) that tax has actually been paid to the government by the supplier. If the registration was cancelled at the invoice date, the tax was not paid, the invoice is not valid for credit, and you are exposed to reversal with interest under s.50 — and in persistent cases to penalty. Recover the tax from the supplier, get a valid invoice from a registered vendor, and document the correction. Rule 21A covers cancellation consequences for the supplier's customers.
What is the difference between ASMT-10 and DRC-01A?
ASMT-10 is an intimation of discrepancy issued under Rule 99 when scrutiny of your returns finds mismatches — you reply in ASMT-11 within 30 days, explaining or rectifying each discrepancy. DRC-01A is a pre-show-cause consultation notice under Rule 142(1A): before issuing a formal DRC-01 demand, the officer gives you a chance to either pay the amount with interest (via DRC-03) or explain in DRC-01B. If the matter is not resolved at the DRC-01A stage, it escalates to a DRC-01 show cause notice, after which s.73/s.74 windows and penalty exposure apply. Both reward a prepared, dated reconciliation register.
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Send us your purchase register, GSTR-2B/2A and last GSTR-3B. We return a dated mismatch register with reasons, the suppliers to chase, and the corrections to file — before the September window closes.
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