Got an Income Tax Notice? What 143(1), 143(1)(a), 139(9) and an AIS Mismatch Mean, and What to Do

An email from the income tax department with a section number in the subject line is enough to ruin an evening. Most of them don’t deserve that. The commonest ones are routine: a summary of how your return was processed, a request to fix a form, or a question about a figure that doesn’t match. They do have deadlines, though, and the cost of ignoring them is usually higher than the cost of answering.

Here is what each common notice means, how long you have, and what to click.

First, check that it is real

Since 1 October 2019, under CBDT Circular 19/2019, every notice, order or letter from the department must carry a computer-generated Document Identification Number (DIN). A communication without one is treated as never issued. The rule has reportedly been reissued under the new Act as Circular 4/2026.

The e-filing portal at incometax.gov.in has an “Authenticate notice/order issued by ITD” service where you can check the DIN without logging in. Do that before you click any link in an email or pay anything. Genuine notices also appear under Pending Actions, e-Proceedings, once you log in. If it isn’t there and the DIN doesn’t verify, treat it as a phishing attempt.

Which notice did you get?

143(1): the intimation almost everyone gets

This is not really a notice. It is the result of the automated processing of your return by the Centralised Processing Centre, sent as a password-protected PDF. The password is normally your PAN in lower case followed by your date of birth (DDMMYYYY).

Section 143(1) only allows limited changes during this processing: arithmetical errors, incorrect claims that are apparent from the return itself, and a few listed items such as income that appears in Form 26AS, 16A or 16 but is missing from the return. It cannot be sent more than nine months after the end of the financial year in which you filed.

Read three numbers on the intimation:

• Income as per return and as computed. If they are the same, nothing changed and you can file it away.
• Refund. If it shows one, it is on its way to the bank account you pre-validated.
• Demand. If there is tax payable, the department changed something. Find the line where the two columns differ. If the change is right, pay it. If it is wrong, respond to the demand on the portal as disagreeing, with reasons, or file a rectification request.

143(1)(a): the warning before the change

Before the department makes any of those adjustments, the first proviso to section 143(1)(a) requires it to tell you, in writing or electronically. The second proviso to section 143(1)(a) says your response will be considered, and “in a case where no response is received within thirty days of the issue of such intimation, such adjustments shall be made.”

On the portal this appears in e-Proceedings as a “Prima Facie Adjustment u/s 143(1)(a)”, and you agree or disagree with each item separately. The most common cause is a figure in your AIS or Form 26AS, interest or a TDS credit, that isn’t in the return. If the department is right, agreeing is the quickest route. If it is wrong, for example the income belongs to another year or another person, disagree and say why. Silence counts as agreement after 30 days.

139(9): the one with a 15-day clock

A defective return notice means the return is missing something the law requires, or is internally inconsistent, for example tax claimed as paid that doesn’t appear in the records, or a return form that doesn’t match the type of income. The notice lists the defect.

Section 139(9) gives 15 days from the intimation to fix it, extendable on request. If you don’t, “the return shall be treated as an invalid return” and the law treats you as not having filed at all, which brings late-filing consequences with it. The Assessing Officer can still condone a late fix made before assessment, but that is discretionary.

To respond, open e-Proceedings, choose Agree and file a corrected return in response to the notice, or choose Disagree and explain why the return is complete.

An AIS mismatch is not a notice yet

Your Annual Information Statement collects what banks, employers, mutual funds and others report about you. When it doesn’t match your return, the department may send an e-campaign email or raise it as a prima facie adjustment.

If the AIS itself is wrong, you can give feedback on each entry on the compliance portal. The options are that the information is correct, not fully correct, relates to another PAN or year, is duplicated, or is denied. The reporting entity is then asked to confirm or correct it. If the AIS is right and the return is wrong, the cleaner fix is the next section.

If you did leave something out: the updated return

An updated return, ITR-U, lets you add income you missed and pay the tax with an extra charge. Since the Finance Act 2025, it can be filed up to 48 months after the end of the relevant assessment year. The extra charge rises the longer you wait: 25%, 50%, 60% or 70% of the tax and interest, depending on the year in which you file. It can’t be used to reduce tax or increase a refund.

The table makes the case for acting early. The same mistake costs ₹3,120 extra in the first year and ₹8,736 extra in the fourth, on top of the ₹12,480 of tax itself.

The section numbers are changing, but not yet for you

The Income-tax Act, 2025 replaced the 1961 Act on 1 April 2026. Some articles now say that 143(1) “is now section 270” or that 139(9) “is now section 263(7)”. Those are the right successor sections, but they apply from tax year 2026-27 onwards. Section 536(2)(c) of the new Act keeps the old Act’s procedure, “including notices, assessment, re-assessment ... rectification”, for every tax year that began before 1 April 2026.

So a notice about your return for FY 2025-26 or any earlier year is still a 143(1) or a 139(9), with the same 30-day and 15-day limits. The new numbers will start appearing on notices about returns for FY 2026-27, filed in 2027.