Section FinderSection 143 of the Income-tax Act, 1961: now section 270
Old section 143 (Assessment) corresponds to section 270 of the Income-tax Act, 2025, according to the Income Tax Department’s navigator. Checked against the Act: the new section is about the same subject.
The first words of the new section
270. (1) Where a return has been made under section 263, or in response to a notice under section 268(1) such return shall be processed in the following manner:— (a) the total income or loss shall be computed after making the adjustments towards the following:— (i) any arithmetical error in the return; or (ii) an incorrect claim, if such incorrect claim is apparent from any inf…
Quoted from the Act as published in the Gazette, only to show which section it is.
Which Act applies
The 2025 Act came into force on 1 April 2026 (its section 1(3)). Income of FY 2025-26 and earlier is dealt with under the 1961 Act (the Act’s section 536 and the CBDT’s transition FAQs, Q1.7 and Q1.12), so for those years the old section number is still the one that applies. For tax year 2026-27 onwards use the new number.
Common questions
What is old section 143 called in the new Act?
section 270 (navigator row: Assessment). checked against the Act: the new section is about the same subject
Does the 1961 section still apply?
For tax years that began before 1 April 2026 the 1961 Act continues to apply (section 536 of the 2025 Act; CBDT FAQs Q1.7 and Q1.12). Under the 2025 Act the new section applies from tax year 2026-27.
Sources
- Income Tax Department, "Section Mapping" navigator (old section of the Income-tax Act, 1961 against the section of the Income-tax Act, 2025; 22 pages, "Section number as per latest draft": it was prepared for the 2025 Bill). Saved by hand by the site owner from incometaxindia.gov.in and read on 13 November 2026.
- The Income-tax Act, 2025 (Act No. 30 of 2025), Gazette of India Extraordinary, 21 August 2025, 572 pages, from egazette.gov.in, read on 13 November 2026: every new section number below was looked up in it (535 of the 536 sections were located in the text).
- CBDT, "FAQs on Interplay and Transition to the Income-tax Act, 2025" (99 pages), saved by hand, read on 13 November 2026; and the Income Tax Department's "Form Mapping Guide" (4 pages), saved by hand, read on 13 November 2026.
Read on 13 November 2026. The Income-tax Act, 2025 came into force on 1 April 2026 (section 1(3)); the 1961 Act continues to apply to tax years before that (section 536 and the CBDT's FAQs). The mapping comes from the department's navigator, which was drawn up for the Bill, and each new number was checked against the enacted Act; rows that could not be checked are marked. This site is independent and not connected with the Income Tax Department; it is a reading aid, not tax advice.