Assessment (Tax) is the process by which the Income Tax Department examines a taxpayer's return and determines the correct tax liability, including any additional tax payable or refund due. Under Indian law, the assessment framework is governed by Sections 143 to 147 of the Income Tax Act, 1961, and encompasses multiple types of assessment — from automated processing to detailed scrutiny to reassessment of previously completed cases.
Legal definition
The Income Tax Act, 1961 does not provide a single definition of "assessment." Instead, it creates a tiered framework:
Section 143(1) — Summary Assessment / Intimation: The return is processed through the Centralised Processing Centre (CPC) without the taxpayer's personal involvement. The CPC checks for arithmetic errors, internal inconsistencies, incorrect claims, and disallowed deductions. An intimation is generated and sent to the assessee. This is not technically an "assessment" but a preliminary processing.
Section 143(2) — Notice for Scrutiny Assessment: If the Assessing Officer (AO) considers it necessary to verify the correctness of the return, a notice is served under Section 143(2) within the prescribed time limit, requiring the assessee to attend the AO's office or produce evidence.
Section 143(3) — Scrutiny Assessment: After examining the evidence, accounts, and information submitted by the assessee, the AO passes an assessment order determining the total income and tax payable. This is the most rigorous form of assessment.
Section 144 — Best Judgment Assessment: Where the assessee fails to file a return, fails to comply with notices, or fails to cooperate with the assessment, the AO makes a "best judgment" assessment based on available information. This assessment can also be made where the AO is not satisfied with the accounts maintained by the assessee.
Section 147 — Reassessment (Income Escaping Assessment): Where the AO has reason to believe that any income chargeable to tax has escaped assessment, the AO may reassess such income by issuing a notice under Section 148. Following the Finance Act, 2021 amendments, a new procedure requiring approval from specified authorities and an information-based trigger was introduced under Sections 148A and 148.
Section 153A — Assessment in case of Search: Where a search is conducted under Section 132, the AO may assess or reassess the total income of the assessee for the six assessment years preceding the search year.
How courts have interpreted this term
GKN Driveshafts (India) Ltd. v. Income Tax Officer (2003) 259 ITR 19 (SC)
The Supreme Court established the procedure for challenging reassessment notices under Section 148. The Court held that when a notice for reassessment is issued, the assessee should file a return and, if they wish to challenge the notice, file objections before the AO. The AO must dispose of the objections by passing a speaking order before proceeding with the reassessment. This procedure — known as the "GKN Driveshafts procedure" — has become the standard protocol for handling reassessment challenges.
Ashish Agarwal v. Union of India (2022) — Supreme Court
The Supreme Court addressed the validity of reassessment notices issued under the old Section 148 regime after the Finance Act, 2021 amendments came into effect. The Court held that all such notices must be treated as show cause notices under the new Section 148A and directed the AOs to follow the new procedure. This landmark ruling affected over 90,000 reassessment notices and established that the new, more taxpayer-friendly reassessment procedure must be followed even for notices originally issued under the old law.
CIT v. Sunbeam Auto Ltd. (2011) 332 ITR 167 (Delhi HC)
The Delhi High Court held that a mere change of opinion by the AO on the same set of facts does not constitute a valid basis for reassessment under Section 147. The AO must have tangible new material or information to justify the belief that income has escaped assessment. This principle has been affirmed by the Supreme Court in multiple decisions.
Why this matters
The assessment framework is the enforcement mechanism of India's self-assessment tax system. While the majority of returns are processed automatically through the CPC under Section 143(1), a significant minority are selected for scrutiny — either through risk-based parameters, data analytics, or information from third-party sources. For taxpayers, receiving a scrutiny notice under Section 143(2) marks the beginning of a detailed examination of their financial affairs.
For businesses and high-net-worth individuals, understanding the assessment timeline is critical. Scrutiny assessments must be completed within the prescribed time limits — currently, 12 months from the end of the assessment year in which the notice was served (for returns filed after the Finance Act, 2016 amendments). Missing this deadline renders the assessment order void. Similarly, reassessment under Section 147 is subject to strict time limits: no notice can be issued after three years from the end of the relevant assessment year unless the income escaping assessment amounts to Rs 50 lakh or more.
Practitioners should note the distinction between regular assessment, which is limited to the return as filed, and reassessment, which reopens concluded assessments. The safeguards against reassessment — including the requirement for the AO to record "reasons to believe," the approval of higher authorities, and the new Section 148A procedure — are designed to protect taxpayers from arbitrary or fishing-expedition reopenings.
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Frequently asked questions
What is the difference between scrutiny assessment and best judgment assessment?
Scrutiny assessment under Section 143(3) is conducted after examining the evidence and accounts produced by the assessee in response to a notice. Best judgment assessment under Section 144 is made by the AO on the basis of available information when the assessee fails to cooperate — either by not filing a return, not responding to notices, or not producing books of accounts. The assessee has fewer procedural protections in a best judgment assessment.
Can a completed assessment be reopened?
Yes. Under Section 147 (read with the new Sections 148 and 148A), the AO can reopen a completed assessment if there is information suggesting that income has escaped assessment. The notice must be issued within three years of the end of the relevant assessment year, extendable to ten years if the escaped income is Rs 50 lakh or more. The AO must follow the Section 148A procedure, including providing the assessee an opportunity to respond before deciding to issue the reassessment notice.
How are cases selected for scrutiny assessment?
Cases are selected through a combination of Computer Aided Scrutiny Selection (CASS) parameters and mandatory selection criteria. CASS uses risk-based algorithms that analyse data from the return, Annual Information Statement (AIS), TDS certificates, and third-party reports to flag returns with high risk of underreporting. Certain categories — such as search cases, cases where information has been received from foreign tax authorities, and cases involving significant additions in prior years — are mandatorily selected.
What is the time limit for completing an assessment?
Under the current provisions (post Finance Act, 2016), a scrutiny assessment must be completed within 12 months from the end of the assessment year in which the notice under Section 143(2) was served. For transfer pricing cases, the time limit is extended by an additional 12 months.
This entry is part of the Veritect Indian Legal Glossary, a comprehensive reference of Indian legal terminology grounded in statutory text and judicial interpretation.
Last updated: 2026-03-27. Veritect provides this content for informational purposes and does not constitute legal advice.