Income Tax Assessment & Reassessment Timelines: What Every Taxpayer Must Know

Most people think filing the return is the end. But that is actually when the Department’s clock starts. This article walks you through every stage, from the first automated check on your return to reassessment, with clear timelines and the latest changes from Finance Bill 2026.

Every year, once the return is filed and the acknowledgement is downloaded, most taxpayers close the chapter and move on, and understandably so.

But from the Department’s side, your return has just entered a process that runs on strict statutory timelines, and those timelines actually work in your favour.

Because every action the Department can take, like; sending an intimation, picking your return for scrutiny, issuing a reassessment notice, must happen within a defined window. If they miss it, they lose the right to act.

So knowing these timelines isn’t just useful for professionals. It helps any taxpayer understand whether a notice they received is even valid, how long they remain “open” after filing, and when they can finally say a year is behind them.

This article walks through the entire process in the order it happens, starting from the very first thing that touches your return after you file.

The Three Stages Your Return Can Go Through

Not every return goes through the same process. There are three possible stages, and most returns only ever see the first one. Here is what each stage looks like:

Stage 01 – Summary Processing

The tax department does an automated check on every return. And in this process, they check your TDS credits, arithmetic and basic deductions. Most people get a clean outcome here.

Stage 02 – Scrutiny Assessment

For selected profiles after stage 1, a detailed examination is triggered. Profiles that are selected based on risk, high-value transactions, large claims and foreign income.

Stage 03 – Income Escaping Assessment/Reassessment

In this stage, the department reopens a case after the original assessment is done or where no return was filed. They have the strictest rules and the most important deadlines.

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Let’s go through each stage in the order they happen, starting with the one that applies to every single return filed in India.

Section 143(1) – The Intimation

The very first thing that happens to your return after filing is an automated check by the Central Processing Centre (CPC) in Bengaluru. There is no human involved here, it is a system that compares what you declared in your return against what is available in your Form 26AS, AIS (Annual Information Statement) and TIS (Taxpayer Information Summary).

What does the system check?

It looks for TDS credits you claimed, but that are not showing in 26AS, deductions under Section 80C crossing the ₹1.5 lakh limit, income appearing in your Form 16 that is missing from the return, or basic arithmetic errors. If it finds something, the intimation will carry a demand. If everything matches, you get a clean “no demand, no refund” intimation.

For most people, the 143(1) intimation is just a confirmation that the return has been accepted as filed. Nothing more needs to be done.

In case the intimation does carry a demand, you generally have 30 days to respond, either paying it or filing a rectification under Section 154 if you believe the processing has made an error. We will cover Section 154 shortly.

One important thing to know: receiving a clean 143(1) intimation does not mean your return cannot be taken up for scrutiny. The two are separate. The intimation just tells you the automated check is done. Scrutiny is a different process, and it is the next stage we need to understand.

Sections 143(2) and 143(3) – Scrutiny Assessment

While the 143(1) intimation is something every return goes through, scrutiny is different; it only applies to returns that get flagged.

The Department uses a system called CASS (Computer Assisted Scrutiny Selection) to identify which returns deserve a closer look, based on several risk factors. Common triggers include large capital gains, significant cash transactions, high deduction claims, foreign income or assets and income that looks unusual compared to earlier years.

Here is how the scrutiny process works:

1. The Scrutiny Notice

This notice is how scrutiny officially begins. It tells you that your return has been selected for detailed examination. And the authorities must issue this within 3 months from the end of the financial year in which the return is furnished.

2. Questions, Replies and Documents

Since 2021, all scrutiny has happened under the Faceless Assessment Scheme, entirely online, through the Department’s portal. The faceless assessment unit raises specific queries, and you must respond with supporting documents and explanations. This can go through several rounds.

3. The Assessment Order

After the process is complete, the Department passes a formal written order. It either accepts your return as filed or makes specific additions or disallowances, with reasons. If you disagree with the order, you have the right to appeal before the Commissioner of Income Tax (Appeals) under Section 246A.

Once scrutiny is done, or if it was never initiated, that year’s assessment is complete. But “complete” doesn’t always mean “closed forever.” The Department can still reopen it, under specific conditions and within strict time limits. That is what reassessment is about.

Sections 147, 148A and 148 – Reassessment

Reassessment is the Department’s power to reopen a case where, after the original assessment is complete, there is reason to believe that some income has “escaped assessment.” The phrase itself comes directly from Section 147 of the Act, and it carries significant weight.

Following the Finance Act 2021 and subsequent amendments, the reassessment process now mandates a two-step approach before any formal reopening notice can be issued. This was a significant reform aimed at preventing arbitrary reassessments.

And let’s now have a look at what actually triggers reassessment?

The AO must have “information” not mere suspicion. Information can come from AIS data, survey or search findings, Directorate of Intelligence reports, or data mismatches from third-party sources. A change of opinion based on already-disclosed facts is not sufficient grounds for a reassessment.

Now let’s have a look at the steps for reassessment:

Step 1: Show Cause Notice

Before they prepare to issue any reassessment notice, the AO must provide the assessee with an opportunity to explain why the case should not be reopened. They are given 7-30 days maximum for the response.

Step 2: Inquiry Order

Once they get a response (if any), the AO passes an order determining whether it is a fit case to issue a reassessment notice. If the AO decides yes, the matter proceeds to Step 3.

Step 3: Reassessment Notice

Once the inquiry process is done, under section 48, a formal notice will be sent to file a return for the relevant assessment year (if already assessed) or to file an original return (if never filed). And this is the notice that opens the reassessment proceedings.

Step 4: Reassessment Order

Once proceedings are initiated, the assessment order must be passed within 12 months from the end of the financial year in which the notice under Section 148 was issued.

The most important question in any reassessment case is: how much income is alleged to have escaped? The time limit for issuing the Section 148 notice is different depending on this number.

The Finance Act No. 2, 2024, revised these limits, effective 1 September 2024:

Here is a real example: for AY 2021-22, if the Department alleges ₹50 lakh or more escaped assessment, it has until 30 June 2027 to issue the notice. But for a smaller amount in the same year, that window already closed on 30 June 2025. A notice issued today for AY 2021-22 on a smaller amount is time-barred. That is a direct legal defence, which is why checking the date and the AY on any notice you receive should always be step one.

Section 154 – Rectification of Errors

Not every error needs an appeal or a reassessment. Section 154 lets both the Department and the taxpayer correct a “mistake apparent from the record”, a TDS credit that was available but not granted, income counted twice, or a basic arithmetic error. The key phrase is “apparent“. If you need to argue a legal position or reopen a factual dispute to prove the mistake, Section 154 won’t work; that belongs in an appeal under Section 246A.

All Timelines in One Place

Here are all the deadlines related to Income tax assessment and reassessment.

Section 148 limits reflect the Finance Act No. 2, 2024 changes effective 1 September 2024. Section 234-I and other Finance Bill 2026 changes take effect from 1 April 2026.

Received a Notice? Here Is What to Do

The table above tells you what the Department can do and when. But when a notice actually arrives, here is what to do with it:

Read the section number first

A 143(1) intimation, a 143(2) scrutiny notice and a 148A show cause are completely different situations. The section tells you what is happening and what you need to do, everything else follows from that.

Check if the notice is within time

Match the notice date against the statutory window from the table above. If it is issued after the deadline, it may have no legal force, and that is your first line of defence, before you even look at the merits.

Verify the Assessment Year and PAN

A wrong AY or PAN on the notice is not a minor typo. Always verify both before responding to anything.

Mark the deadline – and start well before it

Missing a response deadline in scrutiny can lead to a best judgment assessment under Section 144. In reassessment, the Department proceeds without your input. The deadline is not a target; it is an outer limit. Start preparing early.

For a 148A notice, give it your best response

This is the one notice that can stop the entire reassessment before it begins. A well-prepared reply with documents at the 148A(b) stage can result in the AO dropping the case at the 148A(d) order itself.

Get a professional involved early

Scrutiny and reassessment both involve multiple rounds where what you say in one response affects the next. Getting help early, not after things escalate, gives you a much better shot at a clean outcome.

Conclusion

Filing your return on time is the starting point of compliance, not the endpoint. But if you understand what can happen after you file, and more importantly, when it cannot happen, you are in a much better position to handle whatever comes your way.

The Finance Bill 2026 has brought a few meaningful updates:
– the clarifications around the authority issuing reassessment notices,
– the option to file an updated return in response to a 148 notice,
– the integration of penalty into assessment orders from AY 2026-27, and
– the new fee for late revised returns under Section 234-I.

None of these is drastic changes, but they all affect how you should approach your compliance and how you should respond when something comes up.

The time limits in this article are your rights under the law. Know them, track them and use them when you need to.

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