GSTR-2B Mismatch and ITC Protection: The Complete 2026 Playbook

Input tax credit is the single most litigated number in GST. Almost every scrutiny notice, every ASMT-10, every Section 73 demand a business receives ultimately traces back to one question: was this credit available, and was it claimed correctly and in time?

The trouble is that the answer now depends on a chain of moving parts that most businesses still treat as separate problems - the Invoice Management System (IMS), GSTR-2B, the Section 16(4) clock, the 180-day payment rule, the DRC-01C intimation, and, at the far end, an appeal to the GST Appellate Tribunal (GSTAT) against a deadline that, for legacy disputes, falls on 30 June 2026, five days from the date this is written.

This article connects those parts into a single workflow. It is built around one practical question every accounts team asks at least once a month - "this invoice isn't showing in my GSTR-2B; what do I do?" and follows each answer all the way to its conclusion, with the provision, the form, and the time limit at every step.

First, the shift that changed everything: GSTR-2B is now the gate, not the guide

Until a few years ago, GSTR-2B was a reconciliation aid. Today it is the eligibility condition itself. Section 16(2)(aa) of the CGST Act makes credit available only where the invoice has been furnished by the supplier in their GSTR-1 (or IFF/GSTR-1A) and thereby communicated to you - in practice, only where it appears in your GSTR-2B. Possession of a tax invoice is no longer enough.

Two developments hardened this in 2025–26:

• IMS became the statutory plumbing. Section 38 of the CGST Act was substituted by Notification 16/2025-Central Tax dated 17 September 2025, so ITC is now legally tied to the records you accept (or are deemed to accept) in IMS. The procedure was codified by the CGST (Fourth Amendment) Rules, 2025 (Notification 18/2025-Central Tax dated 31 October 2025).
• IMS became mandatory from 1 April 2026 for all regular taxpayers filing GSTR-3B (composition dealers are outside it). The portal is steadily moving toward hard-locking GSTR-3B ITC to what GSTR-2B supports, which means the buyer's only real lever sits inside IMS, before GSTR-2B is generated.

Hold on to one fact that drives half of the decision tree below: IMS lets you accept, reject, or defer the invoices a supplier has reported, it cannot add an invoice the supplier never reported. If a supply isn't in the system, no amount of IMS action will conjure it.

The decision tree: your invoice isn't in GSTR-2B

When an invoice in your purchase register has no match in GSTR-2B, it falls into one of four situations. The response is different in each.

Branch 1: The supplier hasn't filed GSTR-1 at all

If the supplier has not filed (or saved) the invoice in GSTR-1/IFF, it will not appear in IMS and will not appear in your GSTR-2B. There is nothing to "accept."

• What you can claim now: nothing. The Section 16(2)(aa) condition is not met. Claiming it anyway, straight from your purchase register is exactly what later triggers a DRC-01C intimation (see Branch 4) because your GSTR-3B ITC will exceed your GSTR-2B ITC.
• The action: pursue the supplier in writing to file GSTR-1. Use the portal's "communication with taxpayer" facility to create a record. Until the invoice lands in a GSTR-2B, defer the credit.
• The time limit that bites: Section 16(4). If the supplier files so late that the invoice only appears in a GSTR-2B after your Section 16(4) window has closed, the credit is generally lost (more on this clock below). This is why payment leverage matters, see the DRC-03-vs-supplier section.

Branch 2: The supplier filed, but this invoice is missing or wrong

Sometimes the supplier filed GSTR-1 but missed this invoice, used the wrong GSTIN, or reported the wrong value or period.

• The action sits with the supplier. Only the supplier can fix their GSTR-1 - through GSTR-1A for the same period (available until they file that period's GSTR-3B) or through an amendment in a later GSTR-1. IMS will then surface the corrected record for you to accept; the credit flows into the GSTR-2B of the month the correction is reported, not retrospectively.
• Wrong-GSTIN invoices that surface in your IMS but don't belong to you should be rejected, so they don't inflate your 2B.
• The time limit: again Section 16(4) - the corrected invoice must reach a GSTR-2B within your eligibility window. A March invoice corrected only in the following January may fall outside it.

Branch 3 - The invoice was in IMS, but it's been rejected

This is the branch that has changed most, and where authorities are tightening. A rejected record moves to the "ITC Rejected" section of GSTR-2B and does not flow into GSTR-3B - no credit. Rejection happens either deliberately (you rejected it) or by oversight.

• Before GSTR-2B is generated: an IMS action is reversible. If you rejected in error, switch it to Accept and recompute GSTR-2B before you file GSTR-3B.
• After you've filed GSTR-3B for that period: the action is locked. You cannot pull a wrongly-rejected invoice back into that period's 2B. The credit can only be restored if the supplier re-reports the invoice (via GSTR-1A or a later GSTR-1), after which it reappears in IMS for acceptance in a subsequent period - and that re-entry, too, must fall within the Section 16(4) window.
• A caution that practitioners are now flagging: "Reject" is not a neutral parking action. Once you've rejected and filed, recovery depends entirely on the supplier's cooperation. Where there's genuine doubt about an invoice, Pending (defer) is usually safer than Reject - it keeps the record alive on your dashboard without committing you, subject to the one-tax-period limit that now applies to credit notes and certain downward amendments. And note the asymmetry: your rejection does not reduce the supplier's liability; they still owe the tax.

Branch 4 - The invoice is fine for you, but the department disputes it in a notice

Here the invoice may well be in your 2B and validly claimed, yet the department raises a mismatch - most commonly because your GSTR-3B ITC exceeded your GSTR-2B ITC in some month, or because a supplier later defaulted. This is where forms start arriving, and where the rest of this playbook lives:

• DRC-01C (Rule 88D) - a system-generated intimation when your GSTR-3B ITC exceeds your GSTR-2B ITC beyond the prescribed threshold. Part A is the intimation; you reply in Part B within 7 days , either paying the excess (with interest under Section 50) through DRC-03, or explaining the difference with a reconciliation. Ignore it and you can be blocked from filing your next GSTR-1/IFF under Rule 59(6), with escalation to Section 73/74.
• ASMT-10 (Section 61 scrutiny) - an officer-issued notice of discrepancy. You reply in ASMT-11, normally within 30 days , with a reconciliation and primary documents; pay any conceded part via DRC-03. If the officer is satisfied, scrutiny closes with ASMT-12. If not, it escalates.
• DRC-01A → DRC-01 - the pre-show-cause intimation and then the show cause notice itself, under Section 73 (non-fraud) or Section 74 (fraud/suppression). For FY 2024-25 onwards these are unified into the new Section 74A , with a common limitation period and penalties graded by whether suppression is alleged.

The crucial insight for Branch 4: many DRC-01C and ASMT-10 mismatches are not wrong claims at all. The recurring "false positives" we see are import IGST (claimed on the Bill of Entry via ICEGATE, which never passes through GSTR-2B), opening-balance ITC carried from an earlier period, transitional (TRAN) credit, and - increasingly - invoices still sitting Pending in IMS that were claimed from the purchase register before being accepted. Each of these is explainable. The reply, not the panic, is the work: reconcile every figure, attach Bills of Entry, prior-period invoice references, and the IMS status, and ask for closure.

The two clocks you cannot miss

Two independent time limits run underneath the whole tree. Confusing them is a common and expensive error.

Section 16(4) - the claim-by clock. ITC for an invoice or debit note must be claimed by the earlier of 30 November following the end of the financial year, or the date you file that year's annual return (GSTR-9). For FY 2025-26, that means the November 2026 GSTR-3B (due 20 December 2026) - unless you file GSTR-9 first, which slams the window shut early. Two points that catch people out: filing GSTR-9 in, say, October closes the window in October; and re-availing ITC that was reversed under the 180-day rule is not subject to this limit (Rule 37(4)). There is also the one-off retrospective relief in Section 16(5) for FY 2017-18 to 2020-21, where the credit was taken in a return filed up to 30 November 2021 - relevant only to legacy disputes.

The 180-day rule - the pay-your-supplier clock. Under the second proviso to Section 16(2) read with Rule 37, if you don't pay the supplier the invoice value plus tax within 180 days of the invoice date, you must add that ITC back to your output tax liability (with 18% interest under Section 50) in the GSTR-3B following the 180-day mark. Pay later, and you re-avail it - with no Section 16(4) limit on the re-availment, though the interest already paid is not refundable.

Does the 180-day rule interact with GSTR-2B non-reflection? In substance, no - they are different failures. The 180-day rule presumes you had a valid credit (the invoice was in your 2B and claimed) and penalises non-payment to the supplier. Branch 1–3 problems are about the credit never validly arising in the first place. But they meet in one ugly scenario: a buyer claims from the books, doesn't actually pay the supplier, and the supplier never files - exposing the buyer to a 2B-mismatch demand and a 180-day reversal on the same invoice. Don't let an invoice sit in both traps at once.

Separately, Rule 37A (built on Section 16(2)(c), the "supplier must have paid the tax" condition) requires you to reverse credit where the supplier hasn't filed their GSTR-3B/paid by 30 September following the year of your claim; you reverse by 30 November, and re-avail if they later pay.

DRC-03 versus chasing the supplier: how to choose

When credit is at risk, you have two levers, and they are not either/or - they are sequenced by who is at fault and how close the deadline is .

• Chase the supplier when the credit is genuinely yours and recoverable: the invoice is real, you've received the goods/services, and the only problem is that the supplier hasn't reported or paid. Your strongest leverage is money you still owe them - withhold the GST portion (or the balance) until they file GSTR-1 and discharge the tax. This is cheaper than conceding credit, and it directly fixes Branch 1, 2, and supplier-default cases.
• Pay via DRC-03 when the credit is genuinely not available or not worth defending: a clerical over-claim, ITC on a supply that failed a Section 16 condition, or a low-value mismatch where the cost of contesting exceeds the tax. Paying voluntarily (with interest) before the matter hardens into a Section 74A demand caps your exposure and usually pre-empts penalty.

The judgement call is the middle ground - a defensible claim the department is questioning. Here the question is evidentiary, not emotional.

What evidence actually survives a Section 73/74 adjudication

In practice, the buyers who hold their credit at adjudication are the ones who can produce, for the specific invoice in dispute, a coherent bundle: the tax invoice; proof the supply was received (e-way bill, transporter/LR, weighbridge or delivery records, the goods-inward entry); proof of payment to the supplier through banking channels (not cash); the contract or purchase order; and the GSTR-2B/ledger trail showing the credit's path. A reconciliation that ties the disputed figure to its source - period by period - is worth more than any argument about intent.

On the recurring battleground of supplier default - where the department denies your credit purely because the supplier didn't pay (Section 16(2)(c)) or didn't upload (Section 16(2)(aa)) - there is a genuine line of relief from the High Courts. Decisions from the Gauhati, Karnataka, Allahabad and Tripura High Courts have, on their facts, protected bona fide buyers from being punished for a supplier's default, reasoning that the department's remedy lies first against the defaulting supplier. This is a real and useful trend, but treat it as a litigation position, not a planning assumption: it turns on you proving genuineness and good faith, and outcomes vary by facts and bench.

The endpoint: GSTAT and the wall on 30 June 2026

If an adverse order survives the first appeal (the Commissioner (Appeals) order in FORM GST APL-04), the second appeal lies to the GST Appellate Tribunal under Section 112. After eight years without a functioning tribunal, GSTAT began operations on 16 February 2026, and its e-filing portal (efiling.gstat.gov.in) was inaugurated only on 15 June 2026. For the enormous backlog, the limitation rule is unusual and urgent.

The one-page GSTAT pre-deposit and filing checklist

1. Find your deadline first - it is date arithmetic, not strategy.
   • Order communicated before 1 April 2026 → file by 30 June 2026 (the backlog deadline notified by S.O. 4220(E) dated 17 September 2025).
   • Order communicated on or after 1 April 2026 → file within 3 months of communication (Section 112), counted from the date of communication , not the date of the order.
2. Don't be misled by 31 December 2026. That date is only a relaxation of document/scrutiny defects (per the GSTAT order dated 14 May 2026) - it does not extend the appeal limitation. Bar associations have pressed for an extension to 31 December 2026, citing portal instability, and the GSTAT Bar Association, Delhi took the matter to the Delhi High Court; as on 25 June 2026 the Court has issued notice but declined interim relief , and no extension has been granted. Treat 30 June 2026 as the operative deadline.
3. Compute the pre-deposit correctly (Section 112(8)). Pay 100% of the admitted liability, plus an additional 10% of the disputed tax at the GSTAT stage - on top of the 10% already paid at the first appeal (cumulative 20%). The additional pre-deposit is capped at ₹20 crore per enactment (CGST and SGST separately).
4. Pay from the right ledger. The pre-deposit must come through the Electronic Cash Ledger - the portal rejects payment from ITC.
5. Compute the 10% on disputed tax only - exclude interest and penalty from the base.
6. Adjust prior deposits. Amounts already paid during the tribunal-less period under CBIC Circular 224/18/2024-GST are set off against this requirement.
7. File correctly. Use FORM GST APL-05 , electronically, with a complete, indexed bundle - the impugned order, the APL-04, ARN/CRN, grounds of appeal, and supporting records. A separate appeal is needed for each order-in-original.
8. Know your safety nets - and their limits. Section 112(6) lets the Tribunal condone delay by up to a further 3 months on sufficient cause (to roughly 30 September 2026 for backlog orders), but only on a properly drawn application. Once the pre-deposit is paid, Section 112(9) deems recovery of the balance stayed. The Tribunal may decline very small appeals (tax/ITC/penalty of ₹50,000 or less under Section 112(2)).
9. Don't forget the tail. If you win, the pre-deposit is refundable with interest, but you must claim it in RFD-01; neither the refund nor the interest is automatic.

For legacy ITC disputes, the discipline is simple: audit every first-appeal order communicated before 1 April 2026 this week and build a filing calendar against 30 June rather than chasing it on the last day, when an untested portal and a 4.8-lakh backlog are least forgiving.

Frequently asked questions

1. An invoice is in my purchase register but not in GSTR-2B. Can I still claim it?

Not until it appears in a GSTR-2B. Section 16(2)(aa) makes 2B reflection a condition. Claiming from the books anyway is the most common cause of a later DRC-01C intimation. Defer the credit and get the supplier to report it.

2. I rejected an invoice in IMS by mistake and have already filed GSTR-3B. Can I fix it?

Not for that period directly - the action is locked once GSTR-3B is filed. The supplier must re-report the invoice (GSTR-1A or a later GSTR-1); it then returns to IMS for acceptance in a later period, provided you're still within the Section 16(4) window.

3. What's the Section 16(4) deadline for FY 2025-26 ITC?

The earlier of the November 2026 GSTR-3B (due 20 December 2026) or the date you file GSTR-9 for FY 2025-26. Filing the annual return early closes the window early.

4. I got a DRC-01C. Does it mean I've done something wrong?

Not necessarily. It's an automated GSTR-3B-vs-2B comparison. Import IGST, opening-balance ITC, TRAN credit, and invoices still Pending in IMS routinely trigger it even when the claim is correct. Reply in Part B within 7 days - pay via DRC-03 if it's a real over-claim, or explain with a reconciliation if it isn't.

5. When should I just pay through DRC-03 instead of fighting?

When the credit genuinely isn't available, or the disputed amount is too small to justify the cost of contesting. Paying voluntarily with interest before a Section 74A demand crystallises usually pre-empts penalty.

6. The department denied my ITC only because my supplier didn't pay the tax. Is there hope?

There's a real line of High Court relief (Gauhati, Karnataka, Allahabad, Tripura) protecting bona fide buyers, on their facts. It's a litigation position that depends on proving genuineness - useful, but not something to plan around.

7. My GSTAT appeal deadline is 30 June 2026 and the portal keeps failing. What do I do?

File as early as possible; preserve screenshots, error logs, challans and support-ticket numbers, these matter if a limitation dispute arises later. If you genuinely cannot file in time, lodge the appeal as soon as you can with a Section 112(6) condonation application explaining the delay. Don't rely on the 31 December 2026 date, it doesn't extend the limitation, it only relaxes scrutiny of defects. And although an extension to 31 December has been sought (including before the Delhi High Court), none has been granted as on 25 June 2026, so plan around 30 June.

This article is for general information as on 25 June 2026 and is not a substitute for advice on your specific facts. GST timelines and portal behaviour are changing quickly in 2026; confirm current positions on the GST and GSTAT portals and the latest CBIC notifications before acting. 

The author, CA Sundram Gupta, is the founder of Patron Accounting LLP , a CA & CS firm headquartered in Pune with offices in Mumbai, Delhi and Gurugram, advising businesses on GST, income tax, audit and MCA compliance, including ITC disputes and GSTAT appeals.