A founder we spoke to last month had filed every GSTR-3B on time for eighteen straight months. Not one late fee. Then a DRC-01B intimation landed on the portal showing a ₹4.7 lakh gap between what the company had declared as outward supply in GSTR-1 and what it had paid in GSTR-3B. The cause was mundane: three credit notes had been entered in GSTR-1 in March but the corresponding reduction was never carried into the 3B for that month, and a February export invoice had been reported twice. Nobody had reconciled the two returns because both had been filed on time — and "filed on time" had been mistaken for "filed correctly."
This is the single most common GST error in Indian private limited companies, and it is expensive precisely because it accumulates silently across months.
What the law actually requires
GSTR-1 and GSTR-3B are not two versions of the same return. They serve different legal functions under the CGST Act, 2017.
GSTR-1 is a statement of outward supplies filed under Section 37 of the CGST Act read with Rule 59 of the CGST Rules, 2017. It is invoice-level. It reports every B2B invoice, every credit note, every debit note, every export and every amendment. It creates no tax liability by itself — it declares what the liability should be, and it is the data that populates your recipient''s GSTR-2B, which is what allows them to claim input tax credit under Section 16.
GSTR-3B is a summary return-cum-payment challan filed under Section 39 of the CGST Act read with Rule 61. It is summary-level. This is where liability is actually discharged. The amount you type into Table 3.1 and pay through the electronic cash or credit ledger under Section 49 is the amount the department treats as tax paid.
Because they are governed by different sections and filed from different data sets, they can diverge. The Act anticipates this. Rule 88C of the CGST Rules (inserted by Notification No. 26/2022-Central Tax, dated 26 December 2022) provides that where the tax payable per GSTR-1 or IFF for a period exceeds the tax paid per GSTR-3B for that same period by a specified amount and percentage, the system will issue an intimation in Part A of Form GST DRC-01B. The commonly applied trigger is a difference exceeding ₹25 lakh or 20% of the 3B liability, whichever is lower — but the operative figure is what the portal actually applies at the time of the run, and the department has separately been issuing scrutiny notices under Section 61 read with Rule 99 (Form ASMT-10) for far smaller gaps.
Two consequences follow directly from the rule text, and both are the part founders miss:
- You must either pay the differential with interest under Section 50 through Form DRC-03, or file an explanation in Part B of DRC-01B, within seven days of the intimation.
- If you do neither, Rule 59(6)(d) blocks the filing of your next GSTR-1 or IFF entirely. The portal will not accept it. Your customers then cannot see your invoices in their GSTR-2B, and cannot claim ITC under Section 16(2)(aa). Your compliance failure becomes their cash flow problem.
There is a mirror-image rule worth knowing: Rule 88D, inserted in 2023, does the same thing on the input side — issuing Form DRC-01C where the ITC availed in GSTR-3B exceeds the ITC available in GSTR-2B beyond the notified limit. The same seven-day clock and the same GSTR-1 blocking consequence apply.
Practical implications
Interest runs from the original due date, not from the notice. Section 50(1) charges interest at 18% per annum on tax not paid by the due date. If a shortfall originated in a return for April 2025 and is discovered in July 2026, interest accrues for the full fifteen months. On a ₹4.7 lakh shortfall that is roughly ₹1.06 lakh in interest alone before any penalty.
A gap that looks like an error can be treated as suppression. Where the department concludes the shortfall was inadvertent, the demand proceeds under Section 73 — tax plus interest, and a penalty of 10% of tax or ₹10,000, whichever is higher. Where it concludes there was fraud, wilful misstatement or suppression of facts, it proceeds under Section 74 — the same tax and interest plus a penalty equal to 100% of the tax, with a five-year limitation window instead of three. Repeated unexplained gaps across consecutive periods are exactly the pattern that pushes an officer from 73 to 74.
Your GSTIN can be suspended. Rule 21A(2A) permits suspension of registration where a comparison of returns reveals "significant differences or anomalies" indicating contravention. Suspension means you cannot issue tax invoices. For a services company billing monthly, that halts revenue collection.
The mismatch surfaces again at GSTR-9 and 9C. The annual return in GSTR-9 requires Table 4 (outward supplies as declared) to be reconciled against Table 9 (tax paid). Where turnover exceeds ₹5 crore, the GSTR-9C reconciliation statement then reconciles all of it against audited financial statements. A gap you ignored monthly becomes a documented, self-certified discrepancy in an annual filing — which is a far worse position to defend.
It contaminates your MCA and income tax position too. The turnover you declare in GSTR-1 is cross-referenced by the department against the revenue in your financial statements filed in AOC-4 with the ROC and against the turnover reported in ITR-6 and the tax audit report in Form 3CD (Clause 44). Under MCA21 v3, financial data from AOC-4 is captured in structured, machine-readable form rather than as a flat attachment — which makes automated cross-checks against GST turnover materially easier than they were under v2. A company whose GST turnover and AOC-4 revenue diverge without explanation is creating a second, independent inquiry.
Step-by-step: what to do
- Run a 24-month reconciliation before the department does. Download the GSTR-1 summary and the GSTR-3B for each period from the portal and compare Table 3.1(a) of 3B against the taxable value and tax in GSTR-1 for the same month, tax head by tax head — IGST, CGST, SGST and cess separately. Netting across heads hides real errors.
- Classify every difference into one of four buckets. Timing (invoice reported in GSTR-1 in one month, paid in 3B the next — self-correcting, document it). Credit and debit notes (declared in GSTR-1 under Section 34 but not adjusted in 3B — the most common single cause). Amendments (Table 9A/9B/9C entries in GSTR-1 with no 3B counterpart). Genuine short payment (real, and needs to be paid).
- Pay genuine shortfalls voluntarily through Form DRC-03 before a notice issues. Section 73(5) allows payment of tax with interest before the issue of a show cause notice, and Section 73(6) then provides that no notice shall be issued in respect of that amount. Voluntary payment under 73(5) attracts no penalty. This is the single highest-value action available and it closes as soon as a notice lands.
- If a DRC-01B has already issued, calendar the seven days immediately. File Part B on the portal with the reason code and a written explanation, and attach the reconciliation working. If part of the gap is genuine, pay that part via DRC-03 and explain the remainder — a partial payment with a documented explanation is treated far better than a bare denial.
- Fix the process, not just the period. Make the monthly close sequence: (a) generate GSTR-1 data, (b) reconcile it to the books, (c) derive the 3B liability from the reconciled GSTR-1 figures rather than re-keying it from a separate report, (d) reconcile ITC to GSTR-2B before claiming, (e) file. Most mismatches exist because 3B is prepared independently of GSTR-1 by a different person or a different report.
- Reconcile ITC against GSTR-2B every month, not annually. Section 16(2)(aa) permits credit only where the invoice appears in your GSTR-2B. Claiming from purchase records instead of 2B is what triggers Rule 88D and Form DRC-01C.
- Close the year at GSTR-9 with a documented reconciliation file. Keep the working papers. If a Section 73 or 74 proceeding starts two years later, a contemporaneous reconciliation is the difference between an inadvertent-error finding and a suppression finding.
FAQ
Can GSTR-1 and GSTR-3B legitimately differ in a given month?
Yes. Timing differences are normal — an invoice raised on 31 March and reported in the March GSTR-1 may be paid in the March 3B or, if the liability was computed on a different cut-off, appear to lag. What is not legitimate is a difference that persists across periods without explanation.
I filed GSTR-1 with a wrong invoice value. Can I revise it?
No. Neither return can be revised once filed. Corrections are made prospectively through the amendment tables of a subsequent GSTR-1 — Table 9A for B2B invoice amendments, 9B for credit and debit note amendments, 9C for amendments to those notes. The amendment must be made before the deadline in Section 37(3), which is 30 November following the end of the financial year, or the date of filing the relevant annual return, whichever is earlier.
What happens if I ignore a DRC-01B intimation?
Your next GSTR-1 or IFF is blocked under Rule 59(6)(d) until Part B is filed or the amount is paid. Registration suspension under Rule 21A(2A) and a demand under Section 73 or 74 follow. There is no route to a filing extension.
Does an auditor catch this in the statutory audit?
Not reliably. The statutory audit under Section 139 of the Companies Act 2013 tests whether revenue is fairly stated in the financial statements — not whether GSTR-1 agrees with GSTR-3B line by line. That reconciliation only becomes an audited assertion in GSTR-9C, and only where turnover exceeds ₹5 crore. Below that threshold nobody checks it unless you do.
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