GSTR-3B Blocked in FY 2026-27? Causes and How to Fix It

If you have been filing GSTR-3B by entering ITC figures straight from your purchase register, you may have read that from April 2026 the portal rejects any GSTR-3B where ITC is higher than GSTR-2B, under a "Zero Mismatch Policy". We could not find that rule in any GSTN advisory, CBIC notification or GST Council press release. This page was first published on that premise and has been rewritten around what is actually notified.

What is real: the law already limits ITC to invoices in GSTR-2B, an excess claim brings a Form DRC-01C, and a few specific GSTR-3B checks can stop a return from being filed. Here is what they are and how to stay clear of them.

What Is the Zero Mismatch Policy

There is no notified rule by that name. The phrase is used loosely for three real things.

The legal rule. Section 16(2)(aa) of the CGST Act and Rule 36(4) of the CGST Rules (as amended from 1 January 2022) allow ITC only on invoices that the supplier has furnished in GSTR-1 or IFF and that appear in your GSTR-2B. So the credit you are entitled to already matches GSTR-2B.

The follow-up after filing. Rule 88D, inserted by Notification 38/2023-Central Tax dated 4 August 2023, lets the portal compare ITC in GSTR-3B with GSTR-2B. If the excess crosses the limit set on the portal, you get Form DRC-01C and have 7 days to pay with interest through DRC-03 or explain in Part B. The return is filed first; the intimation comes after.

The liability lock. Under GSTN Advisory No. 606 dated 7 June 2025, the liability auto-populated in GSTR-3B from GSTR-1, GSTR-1A and IFF cannot be edited from the July 2025 tax period. This is on outward tax, not ITC.

Several articles describe a lock on ITC in Table 4 as expected in 2026, but none we found cites a dated GSTN advisory. Until one is issued, Table 4A remains editable and DRC-01C is the consequence of an excess claim.

When GSTR-3B Can Actually Be Blocked

These are the verified situations in which the portal stops or restricts filing.

• Reclaimed ITC above the reclaim ledger. GSTN advisories on the Electronic Credit Reversal and Re-claimed Statement (most recently 29 December 2025) state that GSTR-3B will not be filed if ITC reclaimed in Table 4D(1) exceeds the ledger's closing balance plus the reversal in Table 4B(2) of that period.
• RCM ITC above RCM tax paid. Under the same advisory, RCM ITC in Table 4A(2) or 4A(3) cannot exceed the RCM tax paid in Table 3.1(d) plus the closing balance of the RCM Liability/ITC Statement.
• Liability you cannot edit. Since the July 2025 tax period, a wrong outward figure in Table 3 cannot be changed in GSTR-3B. You fix it through GSTR-1A before filing GSTR-3B.
• Returns more than three years old. From the July 2025 tax period, the portal does not accept GSTR-1, GSTR-3B, GSTR-9 and some other returns filed after three years from their due date (Sections 37(5), 39(11) and 44(2), in force from 1 October 2023 under Notification 28/2023-Central Tax; GSTN advisory of 7 June 2025).

An unanswered DRC-01C does not block GSTR-3B. It blocks your next GSTR-1 or IFF under Rule 59(6), which in turn keeps your invoices out of your customers' GSTR-2B.

Check the latest advisories on gst.gov.in for the date each validation applies to your return.

How to Compare GSTR-2B vs GSTR-3B Line by Line

Step 1: Download GSTR-2B

Log in to the GST portal on or after the 14th of the following month. Go to Returns, then GSTR-2B. Download the statement for the relevant period in Excel or JSON format.

Step 2: Map to GSTR-3B Table 4

GSTR-2B is organised into sections that feed different rows of Table 4 in GSTR-3B.

Import of services does not appear in GSTR-2B. You pay that tax under reverse charge and claim it in Table 4A(2).

Step 3: Check Each Row

For each entry in the ITC available section of GSTR-2B, verify:

• Supplier GSTIN matches your purchase records
• Invoice number and date match
• Taxable value and tax amounts (IGST, CGST, SGST) match
• The invoice has not been rejected or kept pending in IMS

Step 4: Identify Differences

Three common scenarios:

1. Invoices in your books but not in GSTR-2B: your supplier has not filed GSTR-1 or IFF for that period. You cannot claim ITC on these invoices until they appear in GSTR-2B.

2. Amount differences: the supplier reported a different taxable value or tax amount. Check the original invoice and ask the supplier to correct it through GSTR-1A or an amendment in a later GSTR-1.

3. ITC on invoices rejected in IMS: if you rejected an invoice in the Invoice Management System, it will not appear as available ITC in GSTR-2B even if it is in your books.

Common Reasons for Mismatches

Supplier Non-Filing

The most frequent cause. If your supplier has not filed GSTR-1 for the period, their invoices will not appear in your GSTR-2B. You have a valid invoice and have paid the tax to the supplier, but you cannot take the credit yet.

What to do: follow up with the supplier immediately, in writing. Track supplier filing compliance monthly.

ITC Reversal Errors

If you reversed ITC in a prior period (under Rule 37 for non-payment within 180 days, or Rules 42 and 43 for common inputs and capital goods used for exempt supplies or non-business purposes), the reclaim goes in Table 4D(1). The portal checks it against the Electronic Credit Reversal and Re-claimed Statement, and a reclaim larger than the recorded reversals can stop the return from filing.

What to do: keep a reversal and reclaim tracker that matches the ledger, and reclaim only after the condition is met (for Rule 37, after paying the supplier).

Timing Differences

Invoices dated in one month but reported by the supplier in the following month create timing gaps. Your books show the ITC for March, but GSTR-2B reflects it in April.

What to do: claim ITC in the period it appears in GSTR-2B, within the Section 16(4) time limit.

Credit Notes Not Accounted

If a supplier issues a credit note reducing the original invoice value, GSTR-2B will reflect reduced ITC. If your books still show the original full credit, there will be a mismatch.

What to do: process all supplier credit notes in your books before preparing GSTR-3B.

IMS Action Mismatches

Acting in IMS is optional, and invoices you do not act on are deemed accepted when GSTR-2B is generated. Invoices you reject, or keep pending, do not count as available credit in that GSTR-2B. If your books still carry them as claimable ITC, the totals will not match.

What to do: align your IMS actions (accept, reject, pending) with your purchase register. You can change actions and recompute GSTR-2B until you file GSTR-3B.

Steps to Resolve Before the Filing Deadline

1. Download GSTR-2B on the 14th of each month (or as soon as it is generated).

2. Run a line-by-line comparison with your purchase register. Use accounting software that imports GSTR-2B, or do it in a spreadsheet.

3. Identify all differences and categorise them: supplier non-filing, amount mismatch, timing difference, or IMS action issue.

4. Contact suppliers with pending GSTR-1 filings. Give them at least 5 days before your filing deadline.

5. Set your GSTR-3B ITC to the figure GSTR-2B supports. Claim only what is available.

6. Track unmatched invoices separately. You can claim the ITC in a later period once it appears in GSTR-2B (subject to the Section 16(4) time limit).

7. Check Table 4D(1) reclaims and RCM ITC against their ledgers, then file GSTR-3B.

What If You Cannot Resolve in Time

If a mismatch cannot be resolved before your GSTR-3B due date (the 20th of the following month for monthly filers, and the 22nd or 24th after the quarter for QRMP filers depending on the state):

• File with the ITC that GSTR-2B supports. Do not inflate ITC.
• Claim the unmatched ITC in a later period once it appears in GSTR-2B.
• If the supplier will not file GSTR-1, consider commercial options such as holding back the tax portion of the payment until the invoice appears.

Filing late to wait for a supplier is usually worse than filing on time with lower ITC. Late filing attracts interest at 18% per annum under Section 50(1) on tax paid in cash, and a late fee of Rs 50 per day (Rs 20 for nil returns), capped per return under Notification 19/2021-Central Tax. For a month-by-month reconciliation calendar, see our GSTR-3B ITC action plan.

Let Tax Garden Handle Your GST Reconciliation

Monthly GSTR-2B reconciliation needs a disciplined process and supplier follow-up. Tax Garden's monthly GST filing service includes GSTR-2B matching, supplier follow-up, and GSTR-3B preparation every month.

Frequently Asked Questions

Can I claim ITC in GSTR-3B for invoices that are not in my GSTR-2B?

Under Rule 36(4), input tax credit can be claimed only for invoices reflected in your GSTR-2B. If a supplier has not filed GSTR-1 or IFF for the period, the invoice will not appear and the credit must wait. Once the supplier files and the invoice shows in a later GSTR-2B, you can claim it in that month, subject to the Section 16(4) time limit.

What happens if the ITC I claim in GSTR-3B is higher than GSTR-2B?

If ITC claimed exceeds the credit available in GSTR-2B beyond the limit set on the portal, you receive an intimation in Form DRC-01C under Rule 88D. You must either pay the excess with interest through DRC-03 or explain the difference in Part B within 7 days. Ignoring the intimation blocks your next GSTR-1 or IFF filing until you respond.

What is the last date to claim ITC on a missed invoice?

Section 16(4) allows ITC on an invoice up to 30 November following the end of the financial year to which the invoice relates, or the date of filing the annual return, whichever is earlier. For FY 2025-26 invoices, that means 30 November 2026 at the latest, so unmatched invoices should be tracked and claimed once they appear in GSTR-2B.

Does rejecting an invoice in IMS affect my GSTR-2B ITC?

Yes. An invoice you reject in the Invoice Management System does not flow into GSTR-2B as available credit, and one kept pending is held back for that period. If your purchase register still counts these invoices as claimable ITC, your GSTR-3B figure will not match GSTR-2B, so align IMS actions with your books before filing GSTR-3B.

When is GSTR-2B generated each month?

GSTR-2B for a month is auto-generated on the 14th of the following month, based on invoices suppliers filed through GSTR-1, IFF and other returns up to their cut-off. With IMS, you can recompute it after acting on invoices, before filing GSTR-3B. Download it right after generation so you have time to chase suppliers before the 20th due date.