Why GSTR-3B Is Getting Blocked in 2026 — The Real Rules Behind the “Zero Mismatch Policy”
Search “GSTR-3B blocked” right now and you’ll find dozens of articles throwing around the term “Zero Mismatch Policy” as if it’s one single rule. It isn’t. What’s actually stopping your return from filing is one of at least three separate, specific GST provisions — and which one has caught you determines exactly how you fix it.
This confusion matters because the advice is different for each. If you’re getting a DRC-01C notice, you have seven days to respond and your return can still be filed while you sort it out. If you’re hitting the newer hard validation checks on your RCM or ITC Reclaim ledgers, filing is blocked outright, no notice period. And if you’re on the July 2026 tax period onward, there’s a fundamentally new layer on top of both — your ITC figures in Table 4 aren’t something you can type in anymore at all.
This piece walks through what “Zero Mismatch Policy” actually refers to on the ground, the specific rule numbers and advisory dates behind each change, and what to do depending on which one is affecting you.
First, What “Zero Mismatch Policy” Actually Means
There’s no GST notification titled “Zero Mismatch Policy.” It’s a phrase that’s grown around a real, multi-year shift in how the GST portal treats the gap between what you claim as Input Tax Credit in GSTR-3B and what your suppliers’ filings actually support in GSTR-2B. The direction of travel has been consistent since 2023: move the check earlier and earlier, from a post-filing notice to a pre-filing wall.
Three separate mechanisms sit under that umbrella, and they’ve arrived in phases:
Rule 88D and DRC-01C (in force since 2023). This is a system-generated intimation, not a block. If your GSTR-3B ITC exceeds GSTR-2B by more than the prescribed threshold, the portal sends Part A of Form DRC-01C to your registered email and portal dashboard. You have seven days to file Part B — either pay the excess through DRC-03 or explain the difference with supporting reconciliation. Ignore it, and the consequence isn’t an immediate GSTR-3B block; it’s that your next GSTR-1 or IFF filing gets blocked under Rule 59(6), with possible escalation to proceedings under Section 73 or 74.
Hard validation checks on specific ledgers (effective 29 December 2025). GSTN moved from advisory-style warnings to actual system blocks for three narrower conditions: reclaimed ITC exceeding the balance in your ITC Reclaim Ledger, RCM ITC claimed beyond your RCM ledger balance, and a negative balance in the Electronic Credit Reversal and Re-claimed Statement (ECRS). Any one of these stops GSTR-3B filing at the point of submission — no notice period, no workaround.
Table 4 (ITC) hard-locking (July 2026 tax period onward). This is the change most businesses haven’t fully absorbed yet, because it’s arriving in the current filing cycle. From the July 2026 period, you can no longer manually type or override the ITC figures in Table 4 of GSTR-3B at all. The numbers are pulled directly from GSTR-2B and your Invoice Management System (IMS) actions. There’s no “claim it anyway and reconcile later” option, because there’s no editable field left to type into.
If you want the short version: DRC-01C is a warning you can still argue with. The ledger checks from December 2025 are a hard stop on specific figures. The July 2026 change removes the ability to manually enter ITC at all. Most of the “my GSTR-3B is blocked” confusion online is people running into one of these three and describing it with the same phrase.
How We Got Here: A Quick Timeline
Understanding the sequence helps explain why this feels sudden even though it’s been building for a while.
| Date | What changed |
|---|---|
| 2023 | Rule 88C (outward liability mismatch) and Rule 88D (ITC mismatch) introduced, backed by DRC-01B and DRC-01C notices |
| 7 June 2025 | GSTN advisory hard-locks auto-populated outward liability — Table 3.1 and 3.2 of GSTR-3B become non-editable |
| July 2025 tax period (filed August 2025) | Outward liability hard-lock takes effect on the portal |
| November 2025 tax period | Table 3.2 (inter-state supplies to unregistered persons, composition taxpayers, UIN holders) also moves to system-generated values only, per GSTN’s advisory of 5 December 2025 |
| 29 December 2025 | GSTN advisory brings in hard system validation for RCM liability, ITC Reclaim Ledger, and ECRS balance — these can now block GSTR-3B filing outright |
| 18 February 2026 | IMS “Rejected Records” tab launches, giving separate visibility into rejected credit and debit notes |
| July 2026 tax period | Table 4 (ITC) hard-locking begins — manual ITC entry in GSTR-3B is discontinued; figures are driven entirely by GSTR-2B and IMS actions |
Two things stand out here. First, this was never a single announcement — it’s been rolled out advisory by advisory over roughly eighteen months. Second, we are, as of this writing, right inside the most disruptive phase of it. If your GSTR-3B for the current period looks different from what you’re used to, this is almost certainly why.
What the Table 4 Hard Lock Actually Changes Day to Day
Until now, even businesses that reconciled sloppily had a safety net: whatever GSTR-2B said, you could still type a different number into Table 4 of GSTR-3B if you were confident the credit was genuinely yours. Auditors and consultants sometimes advised doing exactly this in edge cases — claim now, sort the paperwork out with the supplier afterward.
That safety net is gone from the July 2026 period. Table 4A now pulls directly from what GSTR-2B shows as available, based on your IMS actions on each invoice. There’s no field to override it.
A few practical consequences worth knowing:
- Table 3.1(d) is not part of this lock. RCM liability on import of services, notified services, and purchases from unregistered persons is still a manually entered figure. Don’t assume the whole return has gone hands-off — this one line item still needs your attention every period.
- “Inaction is acceptance” in IMS. If you don’t explicitly reject or mark an invoice as pending, the system treats it as accepted by default, and it flows straight into your GSTR-2B and then into your locked Table 4A. A wrong invoice you simply ignored is now a wrong invoice you’ve effectively claimed.
- Timing of IMS action matters more than before. GSTR-2B generates on the 14th of every month. If you take an IMS action — accepting, rejecting, or un-rejecting an invoice — after the 14th but before you file, you have to manually click “Recompute GSTR-2B” on the IMS dashboard. Skip that step and the portal will use the stale, pre-action version when it populates Table 4A.
- Credit and debit notes need separate attention. The Rejected Records tab, live since 18 February 2026, shows rejected credit and debit notes on their own. If you reject a supplier’s credit note as the recipient, their output liability gets added back on their side — so rejections should be deliberate, not a default response to anything unfamiliar.
Working Through a Reconciliation, Step by Step
Whether you’re dealing with a DRC-01C notice, a ledger-check block, or simply making sure Table 4A comes out correct under the new lock, the underlying reconciliation work is the same. Here’s the sequence that actually catches problems before they become blocks.
Download GSTR-2B as soon as it’s generated, typically the 14th of the month for the prior period. Don’t wait until closer to the filing deadline — that leaves no runway to chase anyone.
Match it against your purchase register line by line. For each entry, check the supplier’s GSTIN, the invoice number and date, the taxable value, and the tax split across IGST, CGST, and SGST. At any real transaction volume, doing this by eye in a spreadsheet is where most reconciliation errors slip through — a single transposed digit in a GSTIN is enough to make a valid invoice fail to match.
Sort every discrepancy into one of four buckets, because the fix is different for each:
- Invoice is in your books but missing from GSTR-2B — almost always because the supplier hasn’t filed their GSTR-1 for the period yet. You genuinely cannot claim this credit until it shows up; there’s no manual override left for this scenario.
- The amount doesn’t match — the supplier reported a different taxable value or tax figure. This needs a conversation with them and an amendment on their side.
- The invoice was rejected in IMS, deliberately or by mistake — check the Rejected Records tab to confirm which, since a mistaken rejection is a common and entirely avoidable loss of credit.
- Timing gap — the invoice is dated for one month but the supplier reported it the next. Claim it in the period GSTR-2B actually reflects it, not the invoice date on paper.
Take IMS action before the 14th where possible, and if you have to act after, remember to hit Recompute GSTR-2B before you go anywhere near the actual filing.
File using only what GSTR-2B supports. This used to be a suggestion. Under the July 2026 lock, it’s the only option that exists — there’s simply nowhere left to enter a higher number.
If a Supplier Won’t Cooperate
The most common cause of a blocked or reduced ITC claim isn’t fraud or a wrong invoice — it’s a supplier who files late or not at all. When that happens and the deadline is close:
File GSTR-3B with the ITC that’s actually available in GSTR-2B for that period. Don’t try to work around it; under the current system there’s no mechanism left to inflate the figure even temporarily. Keep a running log of the specific invoices that are missing, so you can track them across periods rather than losing sight of them. Once the supplier eventually files and the invoice appears in a future GSTR-2B, claim it then — subject to the time limit under Section 16(4) of the CGST Act, which cuts off ITC claims after a fixed window regardless of how legitimate the underlying purchase was.
For suppliers who are chronically late, the practical leverage most businesses actually have is commercial, not legal: withholding the GST portion of payment (or the full balance) until they file. It’s usually far more effective than escalating through the tax authority, and it directly protects your own cash flow rather than just your compliance record.
A Monthly Rhythm That Keeps You Out of Trouble
| When | What to do |
|---|---|
| 1st–13th | Work through last period’s IMS queue — accept, reject, or pend each invoice deliberately; don’t let anything sit unreviewed |
| 14th | Download GSTR-2B the moment it generates |
| 14th–18th | Reconcile line by line against your purchase register; categorise every mismatch |
| Before filing | If any IMS action happened after the 14th, click Recompute GSTR-2B first |
| Ongoing | Enter Table 3.1(d) RCM liability manually — it’s not auto-populated even under the new lock |
| Ongoing | Check your GST portal bank account details and Aadhaar authentication status periodically; an unverified bank record can suspend your registration independent of anything covered here |
Frequently Asked Questions For GSTR-3B Is Getting Blocked in 2026
Is the Zero Mismatch Policy an official GST rule? Not by that name. It’s shorthand people use for a combination of Rule 88D (the DRC-01C notice mechanism), the hard validation checks GSTN introduced from 29 December 2025 for RCM and ITC Reclaim ledgers, and the Table 4 hard-locking that began with the July 2026 tax period. The underlying legal basis is spread across these provisions and advisories, not a single circular.
What’s the actual difference between a DRC-01C notice and a hard block? DRC-01C gives you seven days to respond before consequences kick in, and your return can still be filed in that window. The hard validation checks (RCM ledger, ITC Reclaim Ledger, ECRS balance) and the July 2026 Table 4 lock don’t come with a response window — the portal simply won’t accept the filing until the underlying figures reconcile.
Can I still manually adjust ITC in GSTR-3B if I’m confident the credit is genuinely mine? No, not from the July 2026 tax period onward for Table 4. If the invoice hasn’t appeared in your GSTR-2B via a valid IMS action, there’s no field to enter a different figure. The only path is to wait until the supplier files correctly and the credit appears in a subsequent GSTR-2B.
Does the RCM liability field in Table 3.1(d) get auto-filled too? No — this is a common misconception. Table 3.1(d), covering RCM liability on imports of services, notified services, and purchases from unregistered persons, remains a manually entered figure even after the July 2026 ITC lock. It is separately subject to its own hard validation against the RCM ledger balance, introduced from 29 December 2025.
What happens if I take an IMS action after GSTR-2B has already generated for the period? The change won’t reflect automatically. You need to click “Recompute GSTR-2B” on the IMS dashboard before filing, or the portal will use the version generated on the 14th, before your action.
If I reject an invoice in IMS by mistake, can I fix it? Yes, within the same return period, before GSTR-3B for that period is filed. Once filed, a rejected invoice is excluded from that period permanently. The Rejected Records tab, live since February 2026, is the fastest way to check what’s currently marked rejected before you file.
Does any of this apply to composition scheme taxpayers? No. Composition taxpayers file CMP-08, not GSTR-3B, so neither the DRC-01C mechanism nor the Table 4 hard-lock applies to them directly. It’s still worth keeping accurate purchase records, since composition status itself depends on turnover thresholds that get checked periodically.
This article reflects GSTN advisories and CBIC rules in effect as of July 2026, including the Table 4 hard-locking rolled out from the July 2026 tax period. GST compliance requirements change through periodic notifications — verify current applicability against the latest advisory on the GST portal before relying on any specific figure or deadline for your filing.