Interest calculator for sections 234A, 234B and 234C, with the 234F fee
Late return, short advance tax and missed instalments: interest and the 234F fee, with the month-by-month working.
- YOU BRING
- Tax on total income, TDS and TCS, the filing date and every challan with its date
- YOU GET
- Interest under 234A, 234B and 234C and the 234F fee, with the working
- YOUR DATA
- Worked out in your browser from what you enter. Nothing is uploaded.
Use the tool
- Fill in the details(you are here)
- Read the result(next)
- Download or print(next)
The return
Interest and fee
| 234A | Return filed late ₹0 × 1% × 3 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
What the Interest calculator: 234A, 234B, 234C does
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.
Updated
234A, 234B, 234C interest worked example: AY 2026-27
A return due on 31/07/2026 (Salary, house property, capital gains (ITR-1 / 2)), filed on 20/09/2026. Advance tax was paid in four instalments, each short of what was due. Interest is simple, at 1% a month, a part of a month counts as a whole month, and the amount is rounded down to ₹100 first.
- Tax on total income
- ₹1,50,000
- TDS, TCS and reliefs
- ₹30,000
- Tax after credits
- ₹1,20,000
- Advance tax paid
- ₹70,000
- Return filed
- 20/09/2026
- Total income
- ₹12,00,000
- 234A: tax unpaid on the due date is ₹1,20,000 less ₹70,000, which is ₹50,000. From 01/08/2026 to 20/09/2026 is 2 months, so ₹50,000 at 1% for 2 months is ₹1,000.
- 234B: advance tax of ₹70,000 is below 90% of ₹1,20,000. The unpaid ₹50,000 bears interest from 1 April 2026 to the filing month, 6 months, which is ₹3,000.
- 234C: each instalment is short, so the shortfall of each runs for the months shown in the table below, and the four add up to ₹2,660.
- 234F: the return is late and the lower fee does not apply, so the fee is ₹5,000.
234A ₹1,000, 234B ₹3,000, 234C ₹2,660, 234F fee ₹5,000. Total ₹11,660.
| DUE BY | SHARE OF TAX DUE | REQUIRED | PAID BY THEN | SHORTFALL | MONTHS | INTEREST |
|---|---|---|---|---|---|---|
| 15/06/2025 | 15% | ₹18,000 | ₹10,000 | ₹8,000 | 3 | ₹240 |
| 15/09/2025 | 45% | ₹54,000 | ₹30,000 | ₹24,000 | 3 | ₹720 |
| 15/12/2025 | 75% | ₹90,000 | ₹50,000 | ₹40,000 | 3 | ₹1,200 |
| 15/03/2026 | 100% | ₹1,20,000 | ₹70,000 | ₹50,000 | 1 | ₹500 |
Advance tax instalment dates and the 234C schedule
| TAXPAYER | INSTALMENT | SHARE OF TAX DUE BY THEN |
|---|---|---|
| Other taxpayers | 15 June | 15% |
| Other taxpayers | 15 September | 45% |
| Other taxpayers | 15 December | 75% |
| Other taxpayers | 15 March | 100% |
| Presumptive (44AD / 44ADA) | 15 March (44AD / 44ADA: one instalment) | 100% |
When 234B, 234C and the 234F fee do not apply
| CASE | WHAT THE CALCULATOR SAYS |
|---|---|
| Tax after TDS and TCS is small | Tax after TDS and TCS is under ₹10,000, so no advance tax was due (section 208). |
| Resident senior citizen, no business income | A resident senior citizen with no business or professional income does not pay advance tax (section 207(2)). |
| Advance tax reaches the threshold | Advance tax paid is at least 90% of the assessed tax (₹1,08,000). |
| Presumptive income | Presumptive income: the whole advance tax is due by 15 March. |
| Lower total income, filed late | Filed late; total income up to ₹5 lakh. |
| Filed late, higher total income | Filed late. |
| Filed by the due date | Filed by the due date. |
| Not required to file | Not required to file, so no fee. |
Income tax return due dates for AY 2026-27 and AY 2025-26
| ASSESSMENT YEAR | KIND OF RETURN | DUE DATE |
|---|---|---|
| AY 2026-27 | Salary, house property, capital gains (ITR-1 / 2) | 31/07/2026 |
| AY 2026-27 | Business or profession without tax audit | 31/08/2026 |
| AY 2026-27 | Tax audit cases and companies (extended to 21 November) | 21/11/2026 |
| AY 2026-27 | Transfer pricing report (section 92E) | 30/11/2026 |
| AY 2025-26 | No tax audit | 31/07/2025 |
| AY 2025-26 | Tax audit cases and companies | 31/10/2025 |
| AY 2025-26 | Transfer pricing report (section 92E) | 30/11/2025 |
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.