Explainer · Interest
234a 234b 234c Interest Calculator (India, 2026)
Sections 234A, 234B and 234C of the income tax law charge interest when tax is paid or returns are filed late. They are three separate charges: 234A for filing the return after the due date, 234B for not paying enough advance tax, and 234C for missing the advance tax instalment dates. This guide explains how each is calculated, with the rate and period, so you can estimate the interest yourself before you file, and know how to avoid it next time.
- Common rate: all three charge 1% per month (a part month counts as a full month).
- 234A: late filing, on unpaid tax, from the day after the due date to the date you file.
- 234B: advance tax under 90% of assessed tax, on the shortfall, from 1 April of the assessment year.
- 234C: instalment shortfalls, on each of the four advance tax dates.
- They can stack: a late-filing, under-paid taxpayer can face all three together.
- Portal computes it: the income tax e-filing portal calculates all three automatically at filing.
01The three sections at a glance
All three charge simple interest at 1% per month (or part of a month), but on different amounts and for different periods:
| Section | Charged for | Rate |
|---|---|---|
| 234A | filing the return after the due date | 1% per month on the unpaid tax |
| 234B | paying less than 90% of your tax as advance tax | 1% per month on the shortfall |
| 234C | missing or underpaying an advance tax instalment | 1% per month on each instalment shortfall |
They can apply together. A taxpayer who both missed instalments and filed late can face 234C, 234B and 234A at the same time, each on its own base.
02Section 234A: late filing
Section 234A applies when you file your income tax return after the due date.
- Rate: 1% per month, or part of a month.
- Base: the tax still unpaid after deducting TDS, TCS, advance tax and any self-assessment tax already paid.
- Period: from the day after the due date until the date you actually file.
Note that a part of a month counts as a full month. Filing even one day into a new month adds a full month of interest. If you have no unpaid tax (TDS covered everything), 234A interest is usually nil even if you file late, though a separate late filing fee may still apply.
03Section 234B: advance tax default
Section 234B applies when you were liable to pay advance tax but paid less than 90% of your assessed tax by the end of the financial year.
- Rate: 1% per month, or part of a month.
- Base: the shortfall, that is the assessed tax (after TDS and TCS) minus the advance tax you actually paid.
- Period: from 1 April of the assessment year until the date you pay the balance (usually at filing).
In short, if your advance tax paid is below 90% of what you finally owe, this interest starts running from the first day of the assessment year.
04Section 234C: instalment deferment
Section 234C applies when you did pay advance tax, but not enough by each instalment date. It looks at each of the four instalments separately.
- Rate: 1% per month on the shortfall in each instalment.
- Period: generally three months for the first three instalments and one month for the last (15 March) instalment.
- Thresholds: you should have paid at least 15% by 15 June, 45% by 15 September, 75% by 15 December and 100% by 15 March. A small relief applies for the first two instalments.
234C is about timing within the year, while 234B is about the total being short at year end. The two often appear together.
05A worked example
Take an individual whose total tax after TDS is Rs 1,00,000, who paid no advance tax and files two months after the due date, with the balance paid at filing.
| Charge | Rough calculation | Approximate interest |
|---|---|---|
| 234A | 1% per month on Rs 1,00,000 for 2 months | about Rs 2,000 |
| 234B | 1% per month on Rs 1,00,000 from 1 April to payment (say 5 months) | about Rs 5,000 |
| 234C | 1% on the instalment shortfalls across the four dates | varies with the instalment gaps |
These are illustrative figures to show the method, not your exact liability. The real amounts depend on your dates and how much tax was unpaid at each point. Always compute on your own numbers or let the portal compute it at filing.
06How to estimate and avoid it
To estimate interest yourself: take the unpaid tax, apply 1% for each month (counting a part month as a full month) over the right period for each section, and add the three up where they apply.
To avoid it next time:
- Pay advance tax instalments on the due dates. See how to pay advance tax online for an individual.
- File your return on or before the due date.
- Keep enough TDS or advance tax covering at least 90% of your final tax.
- If you sell property or shares, remember capital gains can create a sudden advance tax liability. Estimate it with the capital gains tax calculator for sale of property.
The income tax portal computes 234A, 234B and 234C automatically when you file, so the filed figure is the one that counts. Your own estimate is useful for planning and for checking the portal's number.
07How Claw Tax helps
Claw Tax and Accounts is an online tax, GST and accounting service for India that connects you with a verified chartered accountant at a fixed, published price, with a Claw reviewer checking every filing before it is submitted.
You can estimate this interest yourself with the method above, and the portal calculates it for you at filing. The useful help is earlier: planning advance tax so the interest never arises, and checking that the computed interest at filing is correct rather than overstated.
Claw Tax can estimate your advance tax, send reminders before each instalment date, and have a verified CA review the final computation so you pay the right interest and no more. Because it is online, this is done at a fixed, published price with a Claw reviewer on the filing. See the services and prices at clawlaw.in/tax.
This is general information, not tax advice; a verified CA handles the specifics of your case.
08Frequently asked questions
What is the difference between 234A, 234B and 234C?
Section 234A charges interest for filing your return after the due date. Section 234B charges interest when your advance tax paid is less than 90% of your total assessed tax. Section 234C charges interest when you miss or underpay the advance tax instalments on their due dates. All three charge 1% per month, but on different amounts and for different periods, and they can apply together.
How is the interest rate calculated under these sections?
The rate is 1% per month, and a part of a month counts as a full month. So filing one day into a new month adds a full month of interest. The amount it is charged on differs: 234A on the unpaid tax, 234B on the shortfall below 90%, and 234C on the shortfall in each instalment. Confirm the current rate and periods, since section numbers may change under the new Income-tax Act.
Can I avoid 234B and 234C interest?
Yes, by paying advance tax on time. If you pay at least 90% of your final tax as advance tax, and meet each instalment threshold (15% by 15 June, 45% by 15 September, 75% by 15 December, 100% by 15 March), you avoid 234B and 234C. Keeping enough TDS also helps. Filing your return by the due date avoids 234A.
Is there an official 234A 234B 234C calculator?
The income tax e-filing portal computes all three automatically when you file your return, based on the dates and amounts you enter, so the filed figure is the authoritative one. You can estimate it yourself beforehand using the 1% per month method for planning, but the portal's computation at filing is what applies.
Do these interest charges apply if I have no tax due?
Largely no. If your TDS and advance tax already cover your full liability, there is usually no unpaid tax for 234A or 234B to apply to, and no instalment shortfall for 234C. A separate late filing fee can still apply if you file after the due date, but that is different from this interest. Always check your own figures.
Does selling property or shares trigger this interest?
It can. A capital gain, for example from selling property or shares, adds to your tax for the year, and if you do not pay advance tax on that gain by the next instalment date, 234B and 234C interest can apply. Estimate the gain early and pay advance tax in the relevant instalment to avoid the interest.