How to Handle Mismatch Between GSTR-1 and GSTR-3B?

Last Updated on August 10, 2026

A gap between what your GSTR-1 says you sold and what your GSTR-3B says you paid tax on doesn’t stay quiet for long. GSTN’s systems compare the two automatically, every month, and once the difference crosses a certain line, you’ll hear about it, first as an automated notice, and later, if ignored, as something with real teeth.

This guide walks through why these mismatches happen, how the department actually catches them, and what to do depending on whether the gap is a genuine error or just a timing difference that will sort itself out.

Why Do These Mismatches Happen?

The most common cause is simple timing. An invoice gets reported in October’s GSTR-1, but the tax on it only gets paid in November’s GSTR-3B, maybe because payment confirmation came in late, or the accounting team just missed the cutoff. Beyond that, you’ve got duplicate or missing invoices, B2B supplies wrongly classified as B2C, credit and debit notes handled inconsistently across the two returns, and the occasional rounding difference that shouldn’t matter but somehow trips the system anyway.

How the Department Actually Catches This?

GSTN runs an analytics engine called ADVAIT that compares your GSTR-1 and GSTR-3B figures every month, at the taxpayer level. Under Rule 88C, if your GSTR-1 liability comes in higher than what you paid in GSTR-3B by more than the threshold, roughly Rs. 1 lakh or 20 percent of your liability, an automated intimation lands in Form DRC-01B. The same kind of discrepancy can also trigger an ASMT-10 scrutiny notice under Section 61, which isn’t automated in the same way and gives you a full 30 days to respond.

Who Ends Up Dealing With This?

• Businesses filing GSTR-1 and GSTR-3B on different schedules, especially under QRMP
• Anyone with a backlog of credit or debit notes that weren’t reconciled promptly
• Businesses that amended a past GSTR-1 without adjusting the corresponding GSTR-3B
• Companies with older, unresolved returns now caught up in the FY 2017-18 to 2019-20 notice surge
• A delayed or unresolved GSTR-1 mismatch doesn’t just affect you; it can delay the corresponding invoice appearing in your buyer’s GSTR-2B, holding up their input tax credit. Worth flagging to B2B customers proactively if a correction is in progress.

Where to Check Pending DRC-01B on the Portal?

Log in to https://www.gst.gov.in/ → Services → Returns → Return Compliance → Liability Mismatch (DRC-01B) tile → View. Pending records and due dates are listed here before the email/portal notification even lands.

Responding to a DRC-01B Notice

You’ve got 7 days from when the intimation lands, and you can’t revise your Part B reply once filed, so this isn’t something to rush through. Broadly, you have two moves. If the gap is a genuine short payment, pay the difference along with interest through Form DRC-03, then reference that ARN in your reply. If it’s a timing issue or a documented error you’ve already fixed, explain it clearly and specifically, citing the invoice number, date, and amount. Part B typically doesn’t let you attach documents, so keep your reconciliation workpapers ready separately in case the officer asks for them later. Talk to our experts to reconcile your GST returns and respond to a mismatch notice.

Fixing the Root Cause

If the mismatch traces back to an error in your GSTR-1, correcting the return itself is usually the right move, using the amendment tables in your next filing: Table 9A for B2B amendments, 9B for credit and debit notes, and 9C for B2C corrections. If it’s a genuine short payment rather than a reporting error, that needs DRC-03 with interest under Section 50, not just a correction in the next period’s GSTR-1.

Using GSTR-1A to Prevent Mismatches Before They Happen?

Since the July 2025 hard-locking of GSTR-3B’s liability fields, GSTR-1A is the only way to correct outward supply errors before filing GSTR-3B; you can no longer fix the number by hand at the GSTR-3B stage.

• File GSTR-1A for the same tax period, before filing GSTR-3B.
• Once GSTR-3B is filed for that period, GSTR-1A can’t be used for it; corrections after that point require a GSTR-1 amendment in a later period instead.
• This shifts the fix upstream: catch the error at GSTR-1/GSTR-1A stage, not after.

What If You Disagree With the Demand?

If a DRC-01B/ASMT-10 explanation is rejected and a formal demand follows under Section 73/74, you can appeal to the Appellate Authority under Section 107 within 3 months of the order (extendable by 1 month), with a mandatory pre-deposit of 10% of the disputed tax. This is the recourse readers actually need once “escalation” happens.

Documents and Records to Keep Ready

• Invoice-level reconciliation between GSTR-1, GSTR-3B, and your books, for every period in question
• Copies of credit and debit notes affecting the disputed period
• DRC-03 payment challans and ARNs, where a voluntary payment has been made

Need help pulling together a clean reconciliation before you respond? Our experts can assist you.

Fees / Cost

There’s no fee for filing a DRC-01B reply or an ASMT-10 response itself. The real cost sits in what you owe if the mismatch turns out to be a genuine short payment: the tax difference, plus interest at 18 percent per annum from the original due date, and a penalty if the case escalates beyond a straightforward correction.

Timeline

Latest Legal Updates

From July 2025, the outward tax liability fields in GSTR-3B auto-populate directly from GSTR-1, GSTR-1A, and IFF, and are no longer manually editable. This closes off a big source of mismatches going forward, since corrections now have to happen at the GSTR-1 level itself. Separately, expect a wave of ASMT-10 notices through early 2026, as the COVID-extended limitation periods for FY 2017-18 through 2019-20 finally run out, pushing the department to act on older, unresolved discrepancies before time runs out.

Penalty / Consequences

• Legal: A confirmed short payment attracts a demand under Section 73, or Section 74 if suppression is alleged
• Financial: Interest runs at 18 percent per annum from the original due date, regardless of when the gap is finally noticed
• Business: Penalties for genuine errors typically run around 10 percent of the tax amount, up to 100 percent where suppression is involved
• Compliance: Ignoring a DRC-01B can block your next GSTR-1 filing under Rule 59(6)

Common Mistakes

• Treating a DRC-01B as optional, since it’s automated and not a formal legal notice yet
• Submitting a vague Part B reply instead of citing specific invoices and reasons
• Fixing the GSTR-1 error but forgetting the corresponding GSTR-3B adjustment, or vice versa

Benefits of Reconciling Every Month

• Catches small, timing-related gaps before they compound into something the system flags
• Keeps your GSTIN off the suspension list tied to persistent, unresolved mismatches
• Makes GSTR-9 a formality instead of a scramble to explain a year’s worth of discrepancies
• Where applicable (turnover above the GSTR-9C threshold), the reconciliation statement specifically reconciles GSTR-1, GSTR-3B, and audited books; unresolved monthly mismatches surface here again at year-end.

Practical Scenario

A distributor’s GSTR-1 for the third quarter shows a higher outward liability than what was actually paid in the corresponding GSTR-3B filings, a gap that built up because a batch of October invoices got reported that month but the tax on them wasn’t paid until November. A DRC-01B lands seven days later. Since the underlying tax has genuinely already been paid, just in the following period, the business replies with a specific explanation, invoice numbers included, and the intimation gets closed out without escalating.

Expert Tips / Best Practices

• Reconcile GSTR-1 against GSTR-3B every month, not just when a notice forces the issue
• Keep a running log of timing differences, so you can explain them quickly if a DRC-01B ever arrives
• Double-check your Part B reply before submitting, since it can’t be revised afterwards

DRC-01B vs ASMT-10: How the Two Processes Differ

How Kanakkupillai Can Help?

We run monthly GSTR-1 to GSTR-3B reconciliations, draft precise, invoice-level replies to DRC-01B and ASMT-10 notices, and handle DRC-03 payments where a genuine short payment needs to be cleared, so a mismatch notice doesn’t turn into a drawn-out dispute.

Conclusion

Most GSTR-1 versus GSTR-3B mismatches are timing issues, not tax evasion, but the system doesn’t know that until you tell it, clearly and within the window you’re given. With GSTR-3B’s liability fields now pulling directly from GSTR-1, the common source of these gaps is fading out, but reconciling every month, rather than waiting for a notice, is still the difference between a five-minute explanation and a demand notice with interest attached. Get expert help reconciling your GST returns and responding to mismatch notices from Kanakkupillai today.

FAQs

1. What triggers an automated DRC-01B notice?

It’s triggered when your GSTR-1 outward tax liability exceeds what you actually paid in GSTR-3B by more than the system threshold, generally around Rs. 1 lakh or 20 percent of your GSTR-3B liability, whichever the system flags.

2. Can I revise my reply to a DRC-01B notice after submitting it?

No, Part B of DRC-01B is a one-time submission and cannot be revised once filed. It’s worth double-checking your explanation and any DRC-03 reference before you click submit.

3. What happens if I ignore a DRC-01B intimation?

Your ability to file the next period’s GSTR-1 or IFF can be blocked under Rule 59(6) until the intimation is addressed, and the matter can also progress toward a formal demand notice.

4. Is every mismatch a sign of tax evasion?

No, most mismatches are timing differences, where an invoice is reported in one month, but the tax is paid in the next. The department generally accepts a clear, documented explanation for these without further action.

5. Does the July 2025 change mean mismatches can’t happen anymore?

It significantly reduces one common source, since GSTR-3B’s liability fields now pull directly from GSTR-1 and can’t be manually altered. Mismatches from earlier periods, or issues on the ITC side against GSTR-2B, can still occur.

6. Why are so many ASMT-10 notices being issued in early 2026?

The COVID-extended limitation periods for FY 2017-18 through 2019-20 are expiring around this time, prompting the department to act on older, unresolved discrepancies before the window to raise a demand closes.