Forms › Assessments, Disputes & GAAR › Form 66

Form 66 — Report for computation of Book Profit (MAT)

Compiled — pending CBDT Appendix III cross-check H · Assessments, Disputes & GAAR
Replaces old Form 29B. Under the Income-tax Act, 2025, this compliance now uses Form 66.
New form numberForm 66
Old form number29B
Act 2025 reference206(1)
CategoryH · Assessments, Disputes & GAAR
Applies fromTax Year 2026-27 (from 1 April 2026)

What is Form 66?

Form 66 is the Income-tax Act, 2025 form titled “Report for computation of Book Profit (MAT)”. It replaces the earlier Form 29B used under the Income-tax Act, 1961 (and the Income-tax Rules, 1962). The purpose of the form is unchanged — the number and format have been updated under the new law.

It falls under the Assessments, Disputes & GAAR category and relates to Section 206 of the Act, and applies to Tax Year 2026-27 (AY 2026-27) onwards, i.e. from 1 April 2026.

A fuller plain-language explainer for Form 66, reviewed by our Chartered Accountants, is being added.

📘 Where this is written in the Act: Form 66 is governed under Section 206 of the Income-tax Act, 2025.
📖 Read Section 206 explained 🔎 Verify in the official Act (PDF)

Transitional rule — which form applies?

⚠️ Which form applies depends on the tax year the compliance relates to, not the calendar date you file. Proceedings for tax years beginning before 1 April 2026 (assessments, appeals, TDS for transactions up to 31 March 2026, and Section 89 relief for those years) continue on the old forms.

Frequently asked questions

What is the new form for Form 29B?

Under the Income-tax Act, 2025, old Form 29B is replaced by Form 66 — Report for computation of Book Profit (MAT). It applies to Tax Year 2026-27 onwards.

From when does Form 66 apply?

It applies to Tax Year 2026-27 (AY 2026-27) onwards, i.e. from 1 April 2026. Compliance relating to earlier tax years continues on the old forms.

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Not sure which form applies to your case?

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This directory is compiled from official CBDT / incometax.gov.in sources and reputable references, and is being reconciled against the Gazette-notified Income-tax Rules, 2026 (Appendix III). Forms marked “compiled” are pending that final cross-check. This is general information, not tax advice.