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Income Tax · Section 234A/B/C

234A/B/C Interest Calculator

Interest under Sections 234A, 234B and 234C is charged at 1% per month (or part of a month). 234A is for late filing of the return, 234B for paying less than 90% of assessed tax as advance tax, and 234C for shortfall in individual advance-tax instalments.

Advance tax paid (cumulative) for 234C

234B applies only if total advance tax paid (the 15 Mar figure) is below 90% of assessed tax. Shortfalls are rounded down to the nearest Rs.100 (Rule 119A). For borderline month-end dates, count each month/part-month as per Section 234B/C.

How 234A, 234B and 234C work

234A — 1% per month on unpaid tax from the due date of filing to the actual filing date. 234B — 1% per month on (assessed tax − advance tax paid) where advance tax is below 90% of assessed tax, from 1 April of the assessment year. 234C — 1% per month on the shortfall in each instalment against the 12%/36%/75%/100% thresholds.

Sections 234A, 234B, 234C, Income-tax Act — simple interest at 1% per month or part thereof; shortfall rounded under Rule 119A.
Caution. 234C has special relief for the first instalment where shortfall arises from capital gains, dividend or lottery income not foreseeable. This tool does not separate such income — compute advance tax on such items separately under Section 234C provisos.

Frequently asked questions

Can 234A and 234B apply together?

Yes. They cover different defaults — late filing (234A) and advance-tax shortfall (234B) — and can both apply in the same year.

Is the interest simple or compound?

Simple interest at 1% per month or part of a month. There is no compounding.

Does part of a month count as a full month?

Yes, for all three sections any part of a month is treated as a complete month.

Key takeaways

  • All three sections charge 1% per month (part = full).
  • 234A: late filing; 234B: <90% advance tax; 234C: instalment shortfall.
  • 234C thresholds: 12% / 36% / 75% / 100% by 15 Jun/Sep/Dec/Mar.
  • Shortfalls rounded down to nearest Rs.100 (Rule 119A).
Related tools: Advance Tax Calculator · Income Tax Calculator

This content is for general guidance only and does not constitute professional advice. Tax law changes frequently — verify the current position and consult a qualified Chartered Accountant before acting. Last reviewed: June 2026.