Changed for Interest Under explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.
The interest charges for late return filing (234A), advance-tax shortfall (234B) and deferment of advance-tax instalments (234C) continue unchanged in substance under the Income-tax Act, 2025 — all at 1% per month, part-month counted in full. Only the section numbers are consolidated; rates, triggers and the ₹10,000 threshold stay the same.
Overview
These three interest heads compensate the exchequer for late or deferred payment of tax. They are compliance costs, not penalties, and the Act 2025 carries them forward almost verbatim, which is good news for predictability.
What the Old Act Said
Under the 1961 Act, section 234A charged 1% per month on unpaid self-assessment tax from the return due date to the actual filing date. Section 234B charged 1% per month where advance tax paid was less than 90% of assessed tax, running from 1 April of the assessment year to payment. Section 234C charged 1% per month for shortfalls in each advance-tax instalment against the 15%/45%/75%/100% cumulative targets due on 15 June, 15 September, 15 December and 15 March. Advance tax itself was payable once liability exceeded ₹10,000, with resident senior citizens (no business income) exempt.
What the New Act 2025 Changes
The Act 2025 consolidates these into its interest provisions but preserves the mechanics entirely. The 1% per month rate applies to all three heads. The 90% test for 234B-type interest, the four instalment dates and cumulative percentages for 234C-type interest, and the ₹10,000 advance-tax threshold all continue. Senior citizens without business income remain outside advance-tax interest. Part of a month is still counted as a full month. In short, the labels "234A/B/C" are now legacy references, but the arithmetic a taxpayer performs is identical.
Old → New Mapping
| Interest head | Trigger | Rate — Act 2025 |
|---|---|---|
| 234A (late filing) | Return filed after due date with tax outstanding | 1% p.m. (continued) |
| 234B (advance-tax default) | Advance tax < 90% of assessed tax | 1% p.m. from 1 April (continued) |
| 234C (deferment) | Shortfall in any of the four instalments | 1% p.m. on the shortfall (continued) |
| Advance-tax threshold | Liability above ₹10,000 | Continued |
| Senior-citizen relief | Resident, no business income | Continued |
Practical Impact / Examples
Say your assessed tax is ₹2,00,000 and you paid only ₹1,50,000 as advance tax (75%, below the 90% mark). 234B-type interest at 1% per month runs on the ₹50,000 shortfall from 1 April until you clear it. If you also filed your return two months late with ₹30,000 still due, 234A-type interest of 2% (2 months × 1%) applies on that ₹30,000. Missing the 15 December instalment triggers 234C-type interest on that quarter's shortfall separately. The heads stack, so paying advance tax on time is the cheapest planning there is.
Transition Tips
- Hit the 90% mark in advance tax to avoid 234B-type interest entirely.
- Respect the four instalment dates (15 Jun / 15 Sep / 15 Dec / 15 Mar) to sidestep 234C-type interest.
- File on time — even a few days late adds a full month of 234A-type interest on outstanding tax.
- Senior citizens with only pension/interest income can ignore advance tax, but must still pay self-assessment tax before filing.