Interest calculator: 234A, 234B, 234C
Late return, short advance tax and missed instalments: interest and the 234F fee, with the month-by-month working.
The return
Interest and fee
| 234A | Return filed late ₹0 × 1% × 2 months | ₹0 |
| 234B | Advance tax under 90% Tax after TDS and TCS is under ₹10,000, so no advance tax was due (section 208). | ₹0 |
| 234C | Instalments short or late Tax after TDS and TCS is under ₹10,000, so no advance tax was due (section 208). | ₹0 |
| 234F | Late-filing fee Filed late; total income up to ₹5 lakh. | ₹1,000 |
| Total | ₹1,000 |
Tax paid
Every challan with its date. Paid by 31/03/2026 counts as advance tax; after that, self-assessment tax.
- ₹1,000 is still to be paid as self-assessment tax before filing: the tax left after advance tax and the challans entered, plus this interest and fee.
Income-tax Act 1961, sections 234A, 234B, 234C and 234F, for assessment years up to 2026-27. Interest is 1% a month, a part of a month counts as a month, and each amount is rounded down to ₹100 (rule 119A). Not modelled: 234C relief for capital gains, lottery or first dividend income arising after an instalment date, and the section 140A order that applies self-assessment tax to interest first when working out 234B. If CBDT extends a due date, check whether the extension also covers 234A before entering it. Check the result before relying on it.
IN SHORT
This free calculator works out interest under sections 234A (return filed late), 234B (advance tax under 90%) and 234C (instalments short or late), and the 234F late-filing fee, for assessment years up to 2026-27. It follows the 1% a month rule with part months counted as whole, rounds each amount down to ₹100, and shows the month-by-month working, ready to export to Excel. Nothing is uploaded.
STEP BY STEP
How it works
- Choose the assessment year and the kind of return; the due date fills itself.
- Enter the tax on total income, the TDS, TCS and reliefs, and the filing date.
- Add every challan with its date. Payments by 31 March count as advance tax, later ones as self-assessment tax.
- Read the interest under each section, the working behind it and what is still to pay, or export it to Excel.
GOOD TO KNOW
Common questions
- When is there no 234B or 234C interest?
- When tax after TDS and TCS is under ₹10,000, because no advance tax was due, and for a resident senior citizen with no business or professional income. 234B also does not apply once advance tax reaches 90% of the assessed tax.
- How are 44AD and 44ADA cases treated?
- Presumptive taxpayers pay all their advance tax in one instalment by 15 March, so 234C is one month's interest on whatever was short on that date.
- How is a part of a month counted?
- As a whole month. A return due on 31 July and filed on 5 August bears one month under 234A; filed on 1 September, two months.
- Does it cover the Income-tax Act 2025?
- Not yet. It covers returns under the 1961 Act, which applies to assessment year 2026-27 and earlier. Returns for tax year 2026-27 onwards will be added when their forms are notified.