Form 66 Income Tax Rules 2026 pdf download and Key points

Last Updated on: April 23, 2026

Form 66 Income Tax Rules 2026 pdf download and Key points

FORM NO. 66
[See rule 137]
Report for Computation of Book Profit for the purposes of section 206(1) of the Act

Under the Income-tax Rules, 2026, Form No. 66 replaces the erstwhile Form 29B. It is governed by Section 206(1) of the Income-tax Act, 2025 (which replaces the old Minimum Alternate Tax sections like 115JB) and Rule 137 of the Income-tax Rules, 2026.

Here are all the key points regarding Form No. 66:

1. Purpose of the Form Form 66 is a statutory report that must be obtained from a Chartered Accountant (CA). It formally certifies the computation of a company’s “book profit” and its corresponding Minimum Alternate Tax (MAT) liability, ensuring the calculations comply with the provisions of Section 206(1).

2. Applicability (Who Should File)

Mandatory Filers: The form applies to every company (whether domestic or foreign) whose total income computed under the regular provisions of the Act results in a tax payable that is lower than the calculated minimum tax (i.e., less than 15% of its book profit, or 9% for IFSC Units).
Exemptions: Section 206 and Form 66 do not apply if the company has opted for the New Tax Regime (under sections 200 and 201 of the IT Act, 2025). Life insurance companies and non-company entities (like Individuals, HUFs, AoPs) whose adjusted total income is ₹20 lakhs or less are also exempt.

3. Frequency and Due Date

Frequency: The form is required to be filed annually.
Due Date: It must be filed electronically on or before the due date of filing the Income Tax Return (ITR) under Section 63, which is typically 31st October for companies subject to audit.

4. Structure of the Form Form 66 contains the independent auditor’s certification and is divided into two main sections:

Part A (Basic Information): Captures the company’s Name, Address, PAN, Email ID, and Contact Details.
Part B: Captures the relevant Tax year, the total income computed under normal provisions, the income-tax payable, and the specific itemized additions and deductions required to accurately calculate the final book profit.

5. Mandatory Documents Required To successfully file Form 66, the following documents and details are required:

Audited Financial Statements (Profit & Loss Account and Balance Sheet).
Computation of total income, book profit, and details of the adjustments made.
Tax audit report.
Digital Signatures (DSC) of both the certifying CA and the company.

6. Process Flow of Filing

Online Only: Form 66 must be filed electronically on the Income Tax Portal.
Workflow: Because it requires an accountant’s certificate, taxpayers cannot fully generate it themselves. A CA computes the book profit, prepares the form, and digitally signs it using their DSC. The company must then log in and accept the report in its e-filing account before submitting its ITR.
Auto-Linkage: Once accepted, the acknowledgment number of Form 66 is auto-linked with the company’s ITR for Central Processing Centre (CPC) verification.

7. Consequences of Default If a company files its ITR but forgets to furnish the CA-certified Form 66, the return will be considered “defective”. The tax officer or CPC may process the return without giving the benefit of MAT credits, leading to a proposed adjustment or a demand notice for higher tax.

8. Key Updates in the 2026 Rules

No Separate Annexures: In the old Form 29B, there were separate annexures and parts. In Form 66, these have been merged directly into the report with proper cross-referencing to the specific clauses and sub-clauses of the new Section 206.
Automation: The new form features auto-validation and data linkage between Form 66 and the ITR, solving previous issues of data mismatches.
Standardization: It utilizes uniform terminology like “Tax Year” and standardizes currency representations using the “₹” symbol.

1. What is Form No. 66 ?
Ans: Form 66 is prescribed for furnishing details related to Computation of Book Profit and Minimum Alternate Tax (MAT) as per provisions of Section 206(1) of Income Tax Act, 2025.
2. What is “Book Profit”?
Ans: It is the profit shown in a company’s profit and loss account, adjusted (increased or decreased) by specific items mentioned in Section 206.
3. What is Minimum Alternate Tax (MAT)?
Ans: Minimum Alternate Tax is the Tax to be paid on Book Profit Computed as per Provisions of Section 206(1) and at the rates mentioned therein. It is a mechanism to ensure that profitable companies paying zero or very little tax due to deductions still pay a minimum amount of tax.
4. Who should file Form 66?
Ans :, All taxpayers which are Company and which are not otherwise required to pay MAT as per Section 206. It applies only if “normal” tax payable by a company is lower than the calculated “minimum” tax.
5. Is Form 66 mandatory?
Ans: It is mandatory for all taxpayers which are Company and if “normal” tax payable by a company is lower than the calculated “minimum” tax.
6. What are exempted entities from MAT?
Ans: The exemption clauses are defined in Section 206 e.g. If the taxpayer has opted for the New-Tax Regime, it is exempted from MAT. Similarly, Individual / HUF / AoP / BoI / AJP, are exempted from AMT if the adjusted total income does not exceed twenty lakh rupees.
7. Does it apply to life insurance companies?
Ans: Section 206 has specific sub-clauses for insurance companies, which are taxed as per the specified rate other than MAT.
8. What is the time limit for filing Form 66?
Ans : It must be filed along with the return of income
9. Do I have to calculate MAT, even if the net income is loss?
Ans: Yes.
10. If my income tax as per regular provisions is more than the MAT, do I have to pay MAT?
Ans: No, the taxpayer has to pay the higher of the two.
11. Can I file Form 66 myself (DIY)?
Ans: Technically, you can log in and upload it, but the form requires a certificate from a Chartered Accountant (CA). You cannot generate this certificate yourself.
12. Why do I need a CA?
Ans: Section 206 mandates that an “Accountant” (CA) must certify that the computation of Book Profit.
13. What happens if I file my ITR but forget Form 66?
Ans: Your return will be considered “defective” or the tax officer will process it without giving you the benefit of MAT credits.
14. Is the form filed online or offline?
Ans: It is filed electronically on the Income Tax Portal.
15. Do I attach the balance sheet to Form 66?
Ans: Form 66 is to be filed alongwith filing of ITR which inter-alia contains the Financial Statements.
16. How is MAT calculated under Section 206?
Ans: The Form 66 has been aligned with the provisions of the Sub-section 1 of the Section 206. Taxpayer needs to fill the respective fields and the MAT will be calculated.
17. What is “MAT Credit”?
Ans: If you pay extra tax today because of MAT, you get a credit for that extra amount. You can use this credit to pay tax in future years as per Section 206, when your Normal Tax is higher.
18. Has the credit mechanism changed in Section 206?
Ans: The mechanism remains the same, however, Section 206 consolidates the credit rules (previously s. 115JAA/115JD of the I.T. Act, 1961). You can still carry forward credit.
19. Can I use MAT credit to pay interest or penalties?
Ans: No, MAT/AMT credit can only be used to pay the tax component, not interest or penalties.
20. Does Section 206 allow for depreciation adjustment?
Ans: Yes, depreciation is one of the main adjustments. The amount of depreciation is adjusted to reach Book Profit.
21. Are capital gains included in MAT?
Ans: Yes, capital gains are part of Book Profit unless specifically identifying as “exempt” income.
22. Does Section 206 consider Ind-AS (Indian Accounting Standards)?
Ans: Yes, Section 206 has specific subsections dealing with “Transition Amounts” for companies following Ind-AS to ensure fair calculation.
23. How to adjust the transition amount ?
Ans: One-fifth of the transition amount in the year of convergence and each of the following four tax years is to be adjusted from the book-profit.
24. What happens if the information in Form 66 is wrong?
Ans: You may receive a notice for “Defective Return” or a demand notice under Section 270(1) of the I.T. Act, 2025 (S. 143(1) of the I.T. Act, 1961) asking for higher tax. You will have to revise the form.
25. Can I revise Form 66?
Ans: Yes, if you discover an error, your CA can file a revised form, and you must then file a Revised ITR.
26. What are the consequences for not obtaining the CA report?
Ans: The return will be defective.
27. Will I get a notice if I don’t file Section 206 forms?
Ans: Yes, the Central Processing Centre (CPC) usually compares your ITR claims with the absence of Form 66 and will likely raise a “Proposed Adjustment” notice.
28. Does Section 206 apply if I opt for the “New Tax Regime” as per S. 200 and S. 201 of the I.T. Act, 2025 (S. 115BAA, S. 115BAB of the I.T. Act, 1961)?
Ans: No, it is exempted.
29. Can a layman calculate the “Book Profit” accurately?
Ans: With the correct understanding of Section 206, anyone can fill the Form, but it should be filed with the certificate of an Accountant. “Book Profit” has over several technical which may require Professional help.
30. What happens if I pay Normal Tax but the Govt says I should have paid MAT?
Ans: You will be asked to pay the difference (Shortfall) plus Interest under Sections 424 and S. 425 of the I.T.Act, 2025 (S.234B and S.234C of the I.T. Act, 1961).
31. Is interest charged if I default on Section 206 payment?
Ans: Yes, interest for default in payment of Advance Tax applies to MAT liabilities just like normal tax.
32. Can I appeal against a Section 206 addition?
Ans: Yes, if the tax officer calculates your Book Profit incorrectly during scrutiny, you can file an appeal before the Commissioner (Appeals).

Form 66 Income Tax Rules 2026 pdf download and Key points

Form 66 Income Tax Rules 2026 pdf download and Key points

Form 66 Income Tax Rules 2026 pdf download

Form No.66– Frequently Asked Questions

Guidance Note on Form 66