Changes in GSTR-3B

Changes in GSTR-3B: The FY 2026-27 Filing Guide Every Registered Taxpayer Needs

GSTR-3B is no longer a five-minute summary return. For FY 2026-27, the CBIC has locked outward liability values from GSTR-1, restructured Table 4 to demand rule-wise ITC reversal disclosure, and introduced automated DRC-01B and DRC-01C intimations for mismatches. If you file GSTR-3B without first reconciling your GSTR-1, GSTR-2B, and books, you are filing blind — and the system will now tell you so, formally, with a notice.

What Has Actually Changed in GSTR-3B for FY 2026-27

Three structural shifts define the current GSTR-3B:

1. Auto-population with progressive locking — outward tax liability in Table 3 flows in from GSTR-1/IFF, and from a notified date, you cannot manually reduce it without an amendment return.
2. Granular ITC reversal disclosure — Table 4(B) now demands rule-wise break-up of reversals, not a single lumped figure.
3. System-generated intimations — Rules 88C and 88D automate the detection of liability under-reporting and excess ITC claims, issuing DRC-01B and DRC-01C respectively.

Together, these changes close three classic loopholes: overstating ITC in GSTR-3B beyond what suppliers reported in their GSTR-1, understating output tax compared to your own GSTR-1, and burying reversal obligations inside an opaque "others" bucket.

Auto-Population from GSTR-1 and GSTR-2B: The Mechanics

Outward Supplies — Table 3

When you save GSTR-1 (or IFF for QRMP taxpayers), the system carries the tax-wise totals — IGST, CGST, SGST — into the corresponding rows of Table 3 of GSTR-3B. This includes:

• Table 3.1(a): Outward taxable supplies (excluding zero-rated and Nil-rated)
• Table 3.1(b): Outward taxable supplies that are zero-rated
• Table 3.1(c): Other outward supplies — Nil-rated, exempted, non-GST
• Table 3.1(d): Inward supplies attracting reverse charge
• Table 3.1.1: Supplies through e-commerce operators liable under Section 9(5)

Table 3.1.1 is new to many filers. If you are an e-commerce operator responsible for paying tax on notified services (transportation, accommodation, housekeeping), this row is mandatory. If your GSTR-1 shows a TCS row for 9(5) supplies but GSTR-3B Table 3.1.1 is blank, expect a scrutiny notice.

Input Tax Credit — Table 4

GSTR-2B, generated on the 14th of the following month after your supplier files GSTR-1, auto-populates Table 4(A) of GSTR-3B. The key distinction: GSTR-2A is dynamic and updates as suppliers file; GSTR-2B is cut at a fixed point and is the legal basis for ITC claims from FY 2022-23 onwards under Section 16(2)(aa) of the CGST Act.

What this means in practice: If your supplier files GSTR-1 on the 13th of a month and you have already filed your GSTR-3B, that ITC will appear in next month's GSTR-2B. Do not claim it early — it will trigger a DRC-01C intimation.

Table 4 Redesigned: Granular ITC Reversal Reporting

This is where most compliance errors now occur. The old Table 4 allowed most reversals to be reported as "others." The revised structure does not.

Table 4(B)(1) — Reversals Under Rules 38, 42, 43 and Section 17(5)

Rule 42 applies when you make both taxable and exempt supplies using common inputs. You must reverse the credit attributable to exempt supplies each month, computed as:

> Reversal = (Exempt supplies ÷ Total supplies) × Common ITC

Rule 43 applies the same proportional logic to capital goods used across taxable and exempt activities, but the computation runs over 60 months.

Rule 38 is sector-specific — banks, NBFCs, and insurers must reverse 50% of ITC on inputs and input services that are not exclusively for taxable supplies, in lieu of maintaining the Rule 42 computation.

Section 17(5) lists blocked credits: motor vehicles (with limited exceptions), food and beverages, club memberships, health insurance for employees (unless mandated), works contract services for construction of immovable property used for own business, and so on. These must now be separately populated in Table 4(D)(1) and reversed in Table 4(B)(1). The old practice of simply not claiming them and leaving 4(B)(1) blank is technically incorrect — if the invoice appears in GSTR-2B, you must show it in 4(A)(5) and simultaneously reverse it in 4(B)(1).

Table 4(B)(2) — Other Reversals

This row captures:

• Rule 37 reversal: If you have not paid your supplier within 180 days of the invoice date, the ITC claimed on that invoice must be reversed here, along with interest under Section 50(3) at 18% per annum from the date of claim.
• Place of supply mismatch: ITC on inputs where the recipient state differs from the GSTIN in whose return you are claiming.
• Any reversal not covered by the named rules above.

Once the vendor is paid (even after 180 days), the credit can be re-availed in 4(A)(5) in the month of payment.

DRC-01B and DRC-01C: What Triggers Them and How to Respond

DRC-01B — Rule 88C: Liability Shortfall

Under Rule 88C of the CGST Rules 2017, if the tax payable as per GSTR-3B is less than the tax payable as auto-populated from GSTR-1 and the difference exceeds the threshold as notified by the Commissioner, the portal generates a DRC-01B intimation asking you to either:

1. Pay the differential tax with interest and file DRC-01B Part B, or
2. Provide a written explanation with documentary evidence of why the difference is valid (e.g., a credit note issued, an amendment to be reflected in next month's GSTR-1).

You must respond within seven days of receiving the intimation. Non-response can result in blocking of the ITC ledger. Typical legitimate explanations include credit notes issued after GSTR-1 filing and pre-GST advance adjustments — but each must be document-supported.

DRC-01C — Rule 88D: Excess ITC Claim

Rule 88D activates when GSTR-3B ITC claimed exceeds GSTR-2B eligible ITC by more than the notified threshold. The DRC-01C intimation follows the same seven-day response window. The taxpayer must either reverse the excess in the current or next GSTR-3B, or justify it (for example, a supplier filed GSTR-1 late and the credit appears in a subsequent GSTR-2B).

Critical point: Interest accrues on the excess ITC from the date of filing GSTR-3B if the excess is not explained or reversed within the specified period.

Worked Example: Rule 42 Reversal and Rule 37 Interest for a Mixed-Supply Firm

Background: Apex Polymers Pvt Ltd (GST-registered, Mumbai) manufactures dutiable plastic granules (taxable, 18% GST) and also sells exempt agricultural mesh (0% GST). For the month of September 2026:

Rule 42 reversal computation:

• Exempt ratio = Rs. 25 lakh ÷ Rs. 1 crore = 25%
• Reversal on common ITC = 25% × Rs. 4,00,000 = Rs. 1,00,000
• ITC exclusively for exempt = Rs. 60,000 (fully reversed)
• Total reversal in Table 4(B)(1) = Rs. 1,60,000
• Net ITC eligible = Rs. 6,00,000 + Rs. 4,00,000 − Rs. 1,60,000 = Rs. 8,40,000

Now add a Rule 37 scenario: In March 2026, Apex claimed ITC of Rs. 80,000 on a supplier invoice. The 180-day payment deadline fell on 1 September 2026. Payment was not made. Apex must reverse Rs. 80,000 in Table 4(B)(2) in the September 2026 GSTR-3B.

Interest under Section 50(3) on the reversed amount:

• ITC claimed: March 20, 2026 (GSTR-3B filing date)
• Reversal date: September 20, 2026 (GSTR-3B for September)
• Period: 184 days
• Interest = 18% × Rs. 80,000 × 184 ÷ 365 = Rs. 7,262 (payable by debit to electronic cash ledger)

This interest does not appear in any auto-populated field — Apex must self-compute and pay it before filing.

The Step-by-Step GSTR-3B Monthly Close (with Actual Dates)

Here is the sequence a financial controller or GST manager should follow for each month in FY 2026-27. The dates below are for a regular monthly filer.

1. By the 11th: File GSTR-1 (or IFF for QRMP). Lock all sales invoices, credit notes, and advances in the ERP. Post-11th corrections require GSTR-1A.

1. 14th: Download GSTR-2B from the GST portal. Run a three-way match against the purchase register and the vendor ledger. Flag invoices in GSTR-2B not in books (duplicate risk) and invoices in books not in GSTR-2B (ITC will be deferred).

1. 15th–17th: Compute Rule 42/43 reversals using the month's exempt and taxable turnover split. Compute Rule 37 reversals for any invoices with 180-day deadline falling in this period. Identify Section 17(5) items in GSTR-2B.

1. 18th–19th: Reconcile Table 3 auto-populated values against the general ledger. If GSTR-1 contains errors (missed credit notes, wrong HSN), file GSTR-1A on the portal before GSTR-3B filing to correct the outward liability — do not simply reduce Table 3 in GSTR-3B without a corresponding amendment.

1. 19th: Compute net cash tax liability (output tax − eligible ITC − previous month carry-forward). Ensure sufficient balance in the electronic cash ledger. Make payment via challan (PMT-06 for QRMP or direct Form GST PMT-06 for others).

1. By the 20th: File GSTR-3B. For QRMP taxpayers with aggregate turnover up to Rs. 5 crore in FY 2025-26, the quarterly GSTR-3B due dates are the 22nd (Category 1 states) or 24th (Category 2 states).

Late fee reminder: Filing GSTR-3B after the 20th attracts a late fee of Rs. 50 per day (Rs. 25 CGST + Rs. 25 SGST) for returns with tax liability, subject to a maximum of Rs. 5,000 per return — plus 18% per annum interest on net cash liability from the due date.

Sector-Specific Reporting Nuances

E-Commerce Operators (Section 9(5))

If you operate a platform through which transportation, accommodation, or housekeeping services are supplied, you pay GST on behalf of the supplier. Report this in Table 3.1.1 (not Table 3.1(a)). The supplier reports their supplies net of 9(5) liability in their own GSTR-3B to prevent double-counting.

Banks and NBFCs (Rule 38)

Instead of maintaining a detailed Rule 42 computation, eligible banking companies may reverse 50% of ITC on all inputs and input services at the entity level each month. The reversal goes into Table 4(B)(1). This is a deemed reversal — you cannot later argue the actual reversal should have been lower.

Real Estate Developers (Rules 42 and 43)

For under-construction projects with a mix of sold and unsold units (liable to GST vs. exempt after OC), the exempt ratio changes month to month. A project with 60% units sold by October 2026 and 80% sold by March 2027 will show a shrinking reversal over the year. Maintain a project-wise calculation sheet and update Table 4(B)(1) every month — do not use a flat annual figure.

Exporters

Exporters claim ITC in full in Table 4(A) — no Rule 42 reversal if there are zero exempt domestic supplies. But track the ITC separately by refund claim batch, because GSTR-3B ITC and refund application data must reconcile during the RFD-01 processing.

Common Mistakes That Lead to Notices

• Claiming ITC not in GSTR-2B: Section 16(2)(aa) now conditions ITC availability on the amount appearing in GSTR-2B. Claiming on the basis of GSTR-2A or physical invoices alone will trigger DRC-01C.

• Not reversing Section 17(5) credits: Many businesses skip the reversal because they never intended to claim — but if the invoice is in GSTR-2B, it auto-populates Table 4(A)(5). You must move it to 4(B)(1) and 4(D)(1). Leaving 4(A)(5) inflated and 4(B)(1) blank creates a false Net ITC figure.

• Applying a single Rule 42 ratio to all months: Rule 42 requires the ratio of exempt turnover to total turnover to be computed each month, with a final true-up in March. Using December's ratio for all months is incorrect and will cause GSTR-9 mismatches.

• Forgetting Rule 37 interest: Reversing the ITC in Table 4(B)(2) is only half the obligation. The interest under Section 50(3) must be self-assessed and paid — the portal will not compute or demand it automatically.

• Editing auto-populated Table 3 downward without an amendment: A common instinct is to reduce the output tax figure if you believe GSTR-1 was overstated. Do not do this in GSTR-3B directly. File GSTR-1A to correct the source data. Editing 3B downward without a matching GSTR-1 amendment guarantees a DRC-01B.

• QRMP taxpayers paying full tax in PMT-06 but not filing GSTR-3B quarterly: PMT-06 is the monthly payment challan; GSTR-3B remains a quarterly filing obligation. Not filing GSTR-3B quarterly (even after making PMT-06 payments) results in late fee accumulation.

GSTR-9 and GSTR-9C: How Monthly Discipline Pays Off at Year-End

Annual return GSTR-9 for FY 2026-27 will be due by 31 December 2027 (subject to extension as notified). Every figure in GSTR-9 traces back to the twelve monthly GSTR-3B returns. Specifically:

• Table 6 of GSTR-9 aggregates ITC taken across all GSTR-3Bs. If your monthly returns correctly bifurcate 4(B)(1) and 4(B)(2), GSTR-9 Table 7 (reversals) fills cleanly.
• Table 9 of GSTR-9 requires you to declare taxes paid — IGST, CGST, SGST, Cess — and reconcile against the electronic ledger. Every late-paid interest amount omitted from a GSTR-3B surfaces here.
• Additional liability discovered during GSTR-9 reconciliation must be discharged via Form DRC-03 — and it attracts interest from the original due date, not from December.

GSTR-9C (reconciliation statement, mandatory for taxpayers with aggregate turnover above Rs. 5 crore in FY 2026-27) requires the auditor to certify that books, GSTR-3B, and GSTR-1 reconcile. The quality of your monthly GSTR-3B — specifically whether Table 4(B)(1) is correctly computed each month — directly determines how many audit observations the GSTR-9C carries.

Taxpayers with disciplined monthly Rule 42 workings typically complete GSTR-9C in two days. Those who lumped reversals into "others" all year spend weeks reconstructing the basis.

Key Takeaways

• Auto-population is the starting point, not the final word. Verify every auto-populated figure in Tables 3 and 4 against your books and GSTR-2B before filing. Discrepancies must be corrected at source (GSTR-1A) rather than manually overridden in GSTR-3B.

• Table 4(B)(1) demands rule-wise reversals. Rules 38, 42, 43 and Section 17(5) blocked credits must each be separately computed and reported — not combined in "others" or left at zero because you didn't intend to claim them.

• DRC-01B and DRC-01C have a seven-day response window. Missing it can lead to ITC ledger restrictions. Respond with documentary evidence or pay the differential tax with interest.

• Rule 37 reversals carry an interest cost you must self-compute. For every invoice unpaid beyond 180 days, reverse the ITC and pay interest at 18% per annum from the date the credit was originally claimed — not from the reversal date.

• The 14th of each month is a hard milestone. GSTR-2B is available on the 14th. Your ITC claim cannot legally exceed what GSTR-2B shows for that period. Build your close calendar around this date, not the 20th filing deadline.

• E-commerce operators must use Table 3.1.1. Section 9(5) tax liability belongs in a separate row, not merged with regular outward supplies. Misreporting creates ITC mismatches for the counter-party supplier.

• Monthly accuracy compresses year-end effort. Every correctly filed GSTR-3B is one less reconciliation item in GSTR-9 and one less observation in GSTR-9C. The cost of getting GSTR-3B right is a few hours each month; the cost of getting it wrong is weeks in December — plus interest, late fees, and DRC-03 payments.