Late Fee and InterestInterest for filing the return late
Section 423 of the Income-tax Act, 2025 charges simple interest of 1% a month on the tax unpaid when a return is filed after the due date. Enter the tax, the due date and the date you filed. Nothing you type leaves your device.
Interest on common amounts, by months late
The rule
I = 1% × A × T, where A is the tax on which interest is payable and T is the number of months in the period beginning the day after the due date and ending on the date the return is furnished (section 423(1)). The tax is the tax on total income as determined, reduced by tax paid, which means advance tax, tax deducted or collected at source and certain reliefs (section 423(4)(d)). Interest already paid as self-assessment interest is reduced from the amount.
The due date is in section 263(1)(c): 31 July for most people, 31 October when accounts are audited, and 30 November in transfer pricing cases. See the due dates.
Common questions
How is interest on a late return worked out?
Section 423: interest = 1% × the tax on which interest is payable × the number of months from the day after the due date to the date the return is furnished. The tax is the tax on the total income reduced by tax paid (advance tax, TDS and similar credits) where no regular assessment is made.
What if I file after the due date but owe no tax?
The interest is worked on the tax still unpaid, so if the tax is already paid by advance tax or TDS the amount is nil. The late filing fee under section 428 is separate.
Is a part of a month counted?
Section 423 speaks of the number of months comprised in the period and does not mention a part of a month; the Act leaves the rounding of a fraction of a month to the Income-tax Rules (not read), so this calculator shows both the count with each started month and the count of complete months.
Sources
- The Income-tax Act, 2025 (Act No. 30 of 2025), as published in the Gazette of India, Extraordinary (egazette.gov.in), read from the PDF on 13 November 2026. Sections used: 263(1)(c) (due dates), 398(3)(a) (late TDS and TCS interest), 423 (late return interest), 424 (advance tax default), 425 (advance tax deferment), 426 (excess refund), 427 (late statement fee), 428 (late return fee).
- Commencement and the repeal of the 1961 Act: section 1(3) (in force on 1 April 2026) and section 536 of the same Act, and the CBDT's "FAQs on Interplay and Transition to the Income-tax Act, 2025" (incometaxindia.gov.in), questions 1.12, 3.5 and 6.1, read on 13 November 2026.
- Counting months: sections 398(3)(a) and 424 say "every month or part of a month", and the CBDT's FAQs (Q on interest for defaults in deducting or depositing TDS and for advance tax, read 13 November 2026) say "per month or part thereof". The Act itself leaves "the rounding off of periods when a fraction of a month is involved" to the rules it empowers the Government to make (the list of rule-making powers, clause (u)); those Income-tax Rules were not read. This site therefore counts every started month, measured from the starting date (28 June to 2 July is one month; 10 January to 12 February is two), which matches "month or part thereof" but the rules may fix the starting-date convention differently. Section 423 itself says only "number of months comprised in the period", so its calculator also shows the whole-month count.
Rates and fees read on 13 November 2026 from the Income-tax Act, 2025 as published in the Gazette. Rules can be amended, and the portal or your assessing officer computes the final amount. This site does the arithmetic and is not tax advice; it is not connected with the Income Tax Department.