GSTR-3B ITC Set-off & Cash Calculator (IGST · CGST

Settings

Leftover IGST credit → CGST / SGST

IGST liability left after IGST credit

Any order was announced in GSTN Advisory 649 (Feb 2026), but the portal has been reported to still force CGST first. Verify on your portal.

Rule 86B applies
Taxable supplies above ₹50 lakh this month and no exemption. At least 1% of output tax must be paid in cash.

Enter amounts (₹)

Result

Late filing interest estimate (optional)

Days late

Lowest cash ledger balance since due date (₹)

Enter the days late to see an estimate.

Estimate = (cash tax payable − lowest cash balance) × days ÷ 365 × 18%, as described for GSTN Advisory 647 (Jan 2026). The portal calculates and locks the real figure in Table 5.1.

Rules this calculator follows

IGST credit pays IGST liability first. Whatever is left may pay CGST and SGST liability in any order and any proportion (Section 49, Rule 88A, Circular 98/17/2019).
CGST credit pays CGST first, then IGST. SGST credit pays SGST first, then IGST. CGST and SGST credit can never be used against each other.
Residual IGST liability can be paid from CGST and SGST credit. GSTN Advisory 649 (19 Feb 2026) allows any order from the February 2026 period, but the portal has been reported to enforce CGST first. Choose accordingly.
Rule 86B: if monthly taxable supplies (excluding exempt and zero-rated) exceed ₹50 lakh, ITC can pay at most 99% of output tax. Exempt if: income tax over ₹1 lakh paid in each of the last two years, a GST refund over ₹1 lakh in the preceding year (zero-rated or inverted duty), cash already above 1% cumulatively this year, or a government body.
Cash only: reverse charge tax, interest, penalty and late fee cannot be paid from the credit ledger.
Compensation cess is not modelled (the tobacco cess ended on 1 Feb 2026).

For estimation and planning only. Set-off rules, advisories and portal behaviour change; confirm the figures on the GST portal and with your tax professional before filing or paying.