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Free · Income Tax Department

Income Tax Interest Calculator (234A, 234B, 234C & 234F)

Work out the interest and late fee the Income Tax Department adds when a return is filed late or advance tax is short, under the 1961 Act sections 234A, 234B, 234C and 234F, or the matching sections 423, 424, 425 and 428 of the Income-tax Act, 2025.

In short: What is interest under section 234A?

Simple interest of 1% for every month or part of a month that your return is filed after the due date, charged on the tax still unpaid after advance tax and TDS. Under the Income-tax Act, 2025 the same rule is in section 423.

Last reviewed against 6 official sources.

Try an example:

Tax year and tax

Advance tax paid (cumulative)

Total paid by each date, not the amount of each instalment

Filing

Interest + late fee

₹10,750

Income-tax Act, 1961 · in addition to tax of ₹40,000 still due

Late return: Section 234A₹40,000 × 1% × 3 months
₹1,200
Short advance tax: Section 234B₹40,000 × 1% × 7 months
₹2,800
Late instalments: Section 234C4 of 4 instalments short
₹1,750
Late-filing fee: Section 234Ftotal income above ₹5 lakh
₹5,000

Instalment check (Section 234C)

DueNeededPaidInterest
15 Jun 2025₹15,000₹10,000₹150
15 Sept 2025₹45,000₹30,000₹450
15 Dec 2025₹75,000₹50,000₹750
15 Mar 2026₹1,00,000₹60,000₹400

Where the interest comes from

Interest and fee total ₹10,750.

The cost of filing later

Filing and paying 3 months later adds about ₹800.

The link holds your numbers in the address. Nothing is sent to us.

How each charge works

Charge1961 Act2025 ActRule
Late return234A4231% a month on unpaid tax, from the day after the due date to filing
Short advance tax234B4241% a month on the shortfall from 1 April, if less than 90% was paid
Late instalments234C4253% on shortfalls at 15 Jun/Sep/Dec, 1% at 15 Mar
Late-filing fee234F428₹1,000 (income up to ₹5 lakh) or ₹5,000

Worked example

A freelancer owes ₹1,00,000 of tax for FY 2025-26 after TDS, with total income of ₹12 lakh. Advance tax paid: ₹10,000 by 15 June, ₹30,000 by 15 September, ₹50,000 by 15 December and ₹60,000 by 15 March. The return, due 31 July 2026, is filed with the balance on 15 October 2026.

  • 234A: ₹40,000 unpaid × 1% × 3 months (August–October) = ₹1,200
  • 234B: only 60% paid, so ₹40,000 × 1% × 7 months (April–October) = ₹2,800
  • 234C: June ₹5,000 short × 3% = ₹150; September ₹15,000 × 3% = ₹450; December ₹25,000 × 3% = ₹750; March ₹40,000 × 1% = ₹400 → ₹1,750
  • 234F: ₹5,000

Total: ₹10,750 on top of the ₹40,000 still owed.

What this calculator simplifies

  • It assumes the balance is paid on the day the return is filed. If you pay self-assessment tax earlier, 234A and 234B stop growing on the amount paid.
  • The 234C relief for under-estimated capital gains, dividends or first-year business income is not modelled.
  • Assessed tax after a department adjustment may differ from your return.

Reading the charts

Each chart redraws as you change the inputs and uses the same calculation as the result above. Choose "Show data" for the exact figures as a table, or download them as a CSV. "Copy link" saves your numbers in the page address so you can come back to the result or share it; nothing is sent to us.

Official sources

Figures last reviewed .

Frequently asked questions

What is interest under section 234A?

Simple interest of 1% for every month or part of a month that your return is filed after the due date, charged on the tax still unpaid after advance tax and TDS. Under the Income-tax Act, 2025 the same rule is in section 423.

When does section 234B interest apply?

If you were liable to pay advance tax (tax of ₹10,000 or more) and paid less than 90% of your assessed tax by 31 March. Interest is 1% a month or part of a month on the shortfall from 1 April until you pay. The new Act's equivalent is section 424.

How is section 234C interest calculated?

Advance tax is due in instalments of 15% by 15 June, 45% by 15 September, 75% by 15 December and 100% by 15 March. A shortfall on the first three dates attracts 3% interest and on 15 March 1%. There is no interest for June if you paid at least 12%, or for September if you paid at least 36%. Under the new Act this is section 425.

What is the late-filing fee under section 234F?

₹1,000 if your total income does not exceed ₹5 lakh, and ₹5,000 otherwise. Under the Income-tax Act, 2025 the fee is in section 428 and the amounts are unchanged.

Which Act applies to my return?

The Income-tax Act, 2025 came into force on 1 April 2026. Income for FY 2025-26 (AY 2026-27) and earlier years is still governed by the Income-tax Act, 1961, so sections 234A–234F apply. From tax year 2026-27 onwards sections 423–428 of the new Act apply, with the same rates.

I use presumptive taxation. Do I pay quarterly?

No. If you declare income under the presumptive scheme (sections 44AD/44ADA, or section 58 of the new Act) you can pay your whole advance tax by 15 March. A shortfall then attracts 1% interest.

How are part months and rupees rounded?

Under Rule 119A any part of a month counts as a full month, and the amount on which interest is charged is rounded down to the nearest multiple of ₹100.

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Disclaimer: This tool gives a general estimate based on what you enter and the published rules. It is not tax, legal or financial advice, and the tax authority makes the final decision. Speak to a qualified professional before acting. See our disclaimer.