Key Takeaways
- The GST portal now blocks GSTR-3B filing entirely if ITC claimed exceeds the amounts shown in GSTR-2B.
- This Zero Mismatch Policy follows the 56th GST Council recommendations and is effective from April 2026.
- Businesses using manual reconciliation processes will hit this block without warning.
- Monthly GSTR-2B reconciliation is no longer optional. It is a filing prerequisite.
If you have been filing GSTR-3B by manually entering ITC figures from your purchase register, that approach no longer works. Starting April 2026, the GST portal enforces a hard block: your GSTR-3B submission will be rejected if the ITC you claim exceeds what appears in your GSTR-2B.
This is not a warning or a notice. It is a technical block that prevents filing.
Here is what changed, why it matters, and how to fix it before your next filing deadline.
Looking for expert help with GSTR-3B filing block resolution and ITC mismatch services? The team at TaxGarden helps Indian SMEs stay compliant end-to-end — filings, notices, and advisory, all in one place.
What Is the Zero Mismatch Policy
The 56th GST Council recommended stricter ITC validation to reduce revenue leakage from fraudulent or inflated input tax credit claims. The result is the Zero Mismatch Policy: the GST portal now performs a real-time comparison between your GSTR-3B ITC figures and your GSTR-2B auto-drafted statement before allowing submission.
Previously, businesses could claim ITC in GSTR-3B that exceeded GSTR-2B amounts. The system would flag the difference through a DRC-01C notice after filing, but filing itself was not blocked. Under the new policy, the portal stops you at the submission stage.
This means you cannot file GSTR-3B until the numbers match.
How the Block Works in Practice
When you attempt to submit GSTR-3B, the portal compares:
- Table 4A of GSTR-3B (ITC claimed by you) against
- GSTR-2B auto-drafted ITC statement (ITC available based on supplier filings)
If the ITC in GSTR-3B exceeds the GSTR-2B amount beyond the permitted threshold, the system rejects your submission. You will see an error indicating that ITC claimed is higher than eligible ITC.
The block applies to each head separately: IGST, CGST, SGST, and cess. A mismatch in any one head can trigger the block.
How to Compare GSTR-2B vs GSTR-3B Line by Line
Step 1: Download GSTR-2B
Log in to the GST portal after the 14th of the month. Navigate 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 organized into sections:
| GSTR-2B Section | Maps to GSTR-3B Table |
|---|---|
| Table 3 (ITC Available) | Table 4A |
| Table 4 (ITC Not Available) | Should not appear in 4A |
| ISD credits | Table 4A(4) |
| Import of goods | Table 4A(1) |
Step 3: Check Each Row
For each entry in GSTR-2B Table 3, 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 marked as "rejected" in IMS
Step 4: Identify Differences
Three common scenarios:
-
Invoices in your books but not in GSTR-2B: Your supplier has not filed GSTR-1 for that period. You cannot claim ITC on these invoices until they appear in GSTR-2B.
-
Amount differences: The supplier reported a different taxable value or tax amount. Verify the original invoice and coordinate with the supplier to amend their GSTR-1.
-
ITC claimed on rejected IMS invoices: 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.
Looking for expert help with monthly GSTR-2B reconciliation and GST compliance management? The team at TaxGarden helps Indian SMEs stay compliant end-to-end — filings, notices, and advisory, all in one place.
Common Reasons for Mismatches
Supplier Non-Filing
The most frequent cause. If your supplier has not filed their GSTR-1 for the period, their invoices will not appear in your GSTR-2B. You have legitimate invoices and have paid GST, but the system does not recognize the credit.
What to do: Follow up with the supplier immediately. Send a formal communication requesting GSTR-1 filing. 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 Rule 42/43 for exempt supplies), and then reclaimed it after meeting conditions, the timing of reversal and reclaim in GSTR-3B must align with GSTR-2B.
What to do: Maintain a reversal and reclaim tracker. Ensure reclaims appear only after the underlying condition is satisfied and reflected in GSTR-2B.
Timing Differences
Invoices dated in one month but reported by the supplier in the following month create timing gaps. Your books show ITC for March, but GSTR-2B reflects it in April.
What to do: Claim ITC in the period it appears in GSTR-2B, not the period of the invoice date in your books.
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
With IMS now mandatory, invoices you rejected or kept pending in IMS will not flow into GSTR-2B as available credit. If your books still carry these as claimable ITC, the totals will not match.
What to do: Align your IMS actions (accept/reject/pending) with your purchase register before the GSTR-2B generation date.
Steps to Resolve Before the Filing Deadline
-
Download GSTR-2B on the 14th of each month (or as soon as it is generated).
-
Run a line-by-line comparison with your purchase register. Use accounting software that supports GSTR-2B import, or do it manually in a spreadsheet.
-
Identify all differences and categorize them: supplier non-filing, amount mismatch, timing difference, or IMS action issue.
-
Contact suppliers with pending GSTR-1 filings. Give them at least 5 days before the filing deadline.
-
Adjust your GSTR-3B ITC figures to match GSTR-2B. Only claim what GSTR-2B shows as available.
-
Track unmatched invoices separately. You can claim the ITC in a future period once it appears in GSTR-2B (subject to the time limit under Section 16(4)).
-
File GSTR-3B with reconciled figures. The portal will now accept your return.
What If You Cannot Resolve in Time
If the mismatch cannot be resolved before your GSTR-3B deadline (typically the 20th of the following month):
- File with GSTR-2B amounts only. Do not inflate ITC.
- Carry forward the unmatched ITC to the next period once it appears in GSTR-2B.
- If the supplier refuses to file GSTR-1, consider the commercial and legal options available, including withholding payment until compliance is confirmed.
Filing late to wait for supplier compliance is worse than filing on time with lower ITC, because late filing attracts interest and late fees.
Let TaxGarden Handle Your GST Reconciliation
Monthly GSTR-2B reconciliation requires disciplined processes and supplier coordination. TaxGarden's Compliance Standard plan includes automated GSTR-2B matching, supplier follow-up, and accurate GSTR-3B preparation every month.
Frequently Asked Questions
What is the Zero Mismatch Policy in GST?
The Zero Mismatch Policy, recommended by the 56th GST Council, means the GST portal blocks GSTR-3B filing if ITC claimed exceeds ITC shown in GSTR-2B. It is a hard filing block, not just a warning notice.
Can I still claim ITC for invoices not in GSTR-2B?
No. Under the new enforcement, only ITC reflected in GSTR-2B can be claimed in GSTR-3B. If an invoice is missing from GSTR-2B because the supplier has not filed GSTR-1, you must wait until it appears.
What is the difference between DRC-01C and the new filing block?
DRC-01C is a post-filing notice issued when ITC exceeds GSTR-2B beyond a threshold. The new filing block is a pre-filing check that prevents GSTR-3B submission entirely. DRC-01C may still apply for minor discrepancies within the threshold.
How often should I reconcile GSTR-2B with my books?
Monthly, as soon as GSTR-2B is generated (14th of each month for monthly filers). Waiting until the filing deadline leaves no time to follow up with suppliers.
Will this block apply to composition scheme taxpayers?
Composition scheme taxpayers file CMP-08 (quarterly statement), not GSTR-3B. The Zero Mismatch Policy applies specifically to GSTR-3B filers. However, composition taxpayers should still verify their input records.
