Interest under 234A, 234B and 234C

Return filed late, advance tax short, instalments missed — the three interest heads worked out separately, with the months and the amount behind each one, so you can check the figure the portal shows.

All calculations happen in your browser — nothing is sent

Financial year

Return due date

31 Jul (non-audit) 31 Oct (audit)

Due date (change it if CBDT extended the date)

Return filed on (leave blank if filed by the due date)

Tax on total income (with surcharge and cess)

TDS / TCS credit

Advance tax paid

Self-assessment tax paid (before the due date)

Rules this calculator applies

Rate: 1% for every month or part of a month. The amount it runs on is rounded down to the nearest ₹100 (Rule 119A).
234A — late return: on the tax still unpaid after advance tax, TDS and self-assessment tax, from the day after the due date to the date of filing. A return due on 31 July and filed on 20 September is two months, not three.
234B — advance tax short: when advance tax paid is less than 90% of the tax after TDS, on the shortfall from 1 April to the date of filing.
234C — instalments: 15%, 45%, 75% and 100% by 15 June, 15 September, 15 December and 15 March; three months of interest on each short instalment and one month on the last. No interest on the first two if at least 12% and 36% was paid.
No advance tax is due — so no 234B or 234C — when the tax after TDS is below ₹10,000. 234A still applies to a late return.

Why the portal can show a different figure

This is an estimate from the figures you enter, the same estimate the PaisaMatch Plus desktop app puts in its ITR computation working paper. The department works 234B up to the date the tax is actually paid and re-computes on the assessed income, and self-assessment tax paid after the due date keeps 234A running until the payment date. Treat the answer as a check, and confirm the final figure.

What this calculator does not do

Presumptive taxpayers under 44AD/44ADA pay one instalment by 15 March — their 234C is different and is not covered.
Capital gains and dividend received after an instalment date are not given the relief the law allows for them.
From FY 2026‑27 the Income-tax Act 2025 applies and section numbers have changed. The maths here follows the old 234A/B/C — confirm the new Act’s sections and rates.