Filing your return late, or paid less advance tax than required? This free CA-built calculator computes all four charges for AY 2025-26 and AY 2026-27 exactly as the Income-tax Act prescribes: interest under Section 234A (late filing), 234B (advance-tax shortfall), 234C (instalment deferment, with the 12%/36% safe harbours and the presumptive-scheme rule) and the Section 234F late fee – with Rule 119A rounding, month-part logic and the correct due dates, including the new 31 August due date for ITR-3/ITR-4 non-audit cases introduced by the Finance Act 2026.
1Basic details
2Tax and payments
Advance tax paid – cumulative by each instalment date (Rs)
Due dates used by this calculator
| Category | AY 2025-26 (as extended) | AY 2026-27 |
|---|---|---|
| ITR-1 / ITR-2 | 16 September 2025 | 31 July 2026 |
| ITR-3 / ITR-4 (no audit) | 16 September 2025 | 31 August 2026 (Finance Act 2026, permanent) |
| Tax audit (44AB) | 10 December 2025 | 31 October 2026 |
| Transfer pricing (92E) | 30 November 2025 | 30 November 2026 |
| Belated return | 31 December 2025 | 31 December 2026 |
How each section works
| Section | When it applies | Rate and period | Base |
|---|---|---|---|
| 234A | Return filed after the due date with tax still unpaid | 1% per month or part, from the day after the due date to the filing date | Tax less advance tax, TDS/TCS, reliefs and self-assessment tax paid by the due date – rounded down to Rs 100 (Rule 119A) |
| 234B | Advance tax paid is less than 90% of assessed tax | 1% per month or part, from 1 April of the AY to the payment/filing date | Assessed tax less advance tax paid |
| 234C | Instalments deferred during the year | 1% for 3 months per shortfall (1 month for the March instalment) | Shortfall vs 15%/45%/75%/100% of tax due on returned income – with 12% and 36% safe harbours for the first two instalments |
| 234F | Return filed after the due date | Flat fee | Rs 5,000 (income above Rs 5 lakh) / Rs 1,000 (up to Rs 5 lakh); nil below the basic exemption unless filing is otherwise mandatory |
Frequently asked questions
My tax was fully paid before the due date but I am filing late. Do I owe 234A interest?
No – where the entire tax stood paid by the due date, 234A interest is nil even if the return is filed late (Prannoy Roy, Supreme Court). The 234F late fee, however, still applies to the late return.
Is the new 31 August due date a one-time extension?
No – the Finance Act 2026 permanently amended Section 139(1): ITR-3 and ITR-4 filers without audit now get 31 August every year. ITR-1 and ITR-2 remain at 31 July.
I paid 13% of my tax by 15 June instead of 15%. Do I pay 234C for that instalment?
No – the safe harbour saves you: no 234C for the June instalment if at least 12% is paid (and none for September if at least 36% is paid). The December and March instalments have no safe harbour.
I am on presumptive taxation (44AD/44ADA). How does 234C apply to me?
You have a single instalment – 100% of advance tax by 15 March. Any shortfall attracts 234C for one month only, and 234B applies if payments fall below 90% of assessed tax by 31 March.
Does 234F apply if my income is below the exemption limit?
Generally no – but if you are otherwise required to file (foreign assets, deposits above Rs 1 crore, foreign travel above Rs 2 lakh, electricity above Rs 1 lakh), the fee applies even below the exemption limit.