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Direct and Indirect Taxation · Self-Assessment and Intimation

Self-Assessment Tax Payment Before Filing the Return

Updated 10 October 2026 · Fact-checked

Self-assessment tax is the tax, interest and fee still unpaid on your return income after crediting advance tax, TDS, TCS and reliefs. Under section 266 of the Income-tax Act, 2025, you must pay it before furnishing the return and attach proof of payment. Any short payment is adjusted first to fee, then interest, then tax.

Understand Self-Assessment of Tax and Payment Before Filing

When you file a return, you declare your total income and compute the tax on it. Advance tax, TDS and TCS may already have covered part of that tax. Whatever is still unpaid is the self-assessment tax.

Section 266(1) puts the duty on you, not on the department. If tax is payable on the basis of a return under section 263, 268, 280 or 294, you must pay that tax together with interest and fee before furnishing the return. The return must be accompanied by proof of payment of the tax, interest and fee.

The tax is payable after taking into account the credits in section 266(2). These include tax already paid, TDS and TCS, relief under section 157, foreign tax relief under sections 159 and 160, the tax credit items listed in clause (f), and any tax or interest payable under section 391(2). The fee and interest payable are those for delay in furnishing the return, or default or delay in payment of advance tax.

The interest is computed on defined bases. Section 423 interest is computed on the tax on the declared total income reduced by advance tax, TDS or TCS, reliefs and the listed credits. Section 424 interest is computed on the assessed tax, or on the shortfall of advance tax against the assessed tax.

If you pay less than the full amount, section 266(3) fixes the order: fee first, then interest, then tax. After a regular assessment under section 270 or 271 or an assessment under section 294, the amount you paid is deemed paid towards that assessment (section 266(7)). If you fail to pay, you are deemed an assessee in default for the unpaid amount (section 266(8)).

Key rules to remember

Self-assessment tax payable
Tax on declared total income − advance tax − TDS/TCS − section 266(2) reliefs and credits, plus interest and fee payable
Pay this before furnishing the return. Interest and fee are added to the payment, not deducted.
Order of adjustment on short payment
Fee first → interest next → tax last
Section 266(3). The balance, if any, goes to tax.
Base for interest under section 423
Tax on declared total income − advance tax − TDS/TCS − reliefs and credits in section 266(4)
Section 266(4) prescribes the base on which interest under section 423 is computed.
Base for interest under section 424
Assessed tax, or the amount by which advance tax paid falls short of assessed tax
Assessed tax is tax on declared total income less TDS/TCS on income included in total income, and the reliefs and credits in section 266(6).
Credit of payment on assessment
Amount paid under section 266(1) is deemed paid towards the regular assessment
Section 266(7), after an assessment under section 270 or 271 or section 294.
Consequence of non-payment
Unpaid tax, interest or fee makes you an assessee in default
Section 266(8), without prejudice to other consequences under section 266(9).

How to solve Self-Assessment of Tax and Payment Before Filing questions

Use the same sequence for any question on self-assessment tax. Work in this order so no credit is missed.

  1. 1Compute the total income and the tax on it, including any surcharge and cess given in the question.
  2. 2List all credits allowed under section 266(2): advance tax, TDS, TCS, section 157 relief, foreign tax relief and other listed credits.
  3. 3Deduct the credits from the tax to find the tax still unpaid.
  4. 4Compute the interest and fee payable, using the bases in section 266(4) and (6) for the interest, and add them to the tax.
  5. 5State the total payable before furnishing the return and note that proof of payment must accompany the return.
  6. 6If the payment made is less than the total, apply it to fee first, then interest, then tax, and show the balance of tax left.
  7. 7If the question mentions a later assessment, state that the amount paid is deemed paid towards that assessment.

Quickest way: Credits first, then fee, interest, tax

When to use it: Use for numerical questions with a short payment or a list of credits.

  1. Write tax liability and subtract every credit in one column.
  2. Add fee and interest given in the question to get the payable total.
  3. For a part payment, fill fee, then interest, then tax from the amount paid.
  4. Write the leftover tax as the unpaid balance, which is in default.

Common mistakes in Self-Assessment of Tax and Payment Before Filing

  • Paying self-assessment tax after filing the return

    Students think the return comes first and payment follows.

    Fix: Remember section 266(1)(a): pay before furnishing the return, and attach proof of payment.

  • Adjusting a part payment first to tax

    Tax feels like the main liability, so it seems to come first.

    Fix: Section 266(3) reverses it: fee, then interest, then tax. Write the order in the answer.

  • Ignoring credits such as TCS or foreign tax relief

    Students remember only advance tax and TDS.

    Fix: Go through the section 266(2) list one item at a time before computing the balance.

  • Using the same base for interest under sections 423 and 424

    Both are interest computed under section 266, so the two bases look alike.

    Fix: Section 423 uses tax on declared income less credits in section 266(4). Section 424 uses assessed tax, or the shortfall of advance tax against it.

  • Forgetting that the payment is credited on assessment

    Students stop at the payment and ignore later assessment.

    Fix: Add one line citing section 266(7): the amount is deemed paid towards the regular assessment.

  • Using the old 1961 Act terms such as assessment year

    Older notes still circulate.

    Fix: Use tax year and the Income-tax Act, 2025 section numbers only.

Worked examples

Example 1

Ravi Menon computes tax on his declared total income for tax year 2026-27 at ₹1,80,000. Advance tax paid is ₹60,000 and TDS is ₹70,000. Interest payable for advance tax default is ₹4,000 and fee for late filing is ₹5,000. Compute the amount he must pay before furnishing the return.

Show the solution
  1. Tax on declared total income = ₹1,80,000.
  2. Credits under section 266(2): advance tax ₹60,000 + TDS ₹70,000 = ₹1,30,000.
  3. Tax still payable = ₹1,80,000 − ₹1,30,000 = ₹50,000.
  4. Add interest ₹4,000 and fee ₹5,000.
  5. Total = ₹50,000 + ₹4,000 + ₹5,000 = ₹59,000.

Answer: Ravi must pay ₹59,000 before furnishing the return and attach proof of payment (section 266(1)).

Example 2

Using the figures of Ravi Menon above, suppose he pays only ₹30,000 before filing. Show how the amount is adjusted and what remains unpaid.

Show the solution
  1. Amounts due: fee ₹5,000, interest ₹4,000, tax ₹50,000.
  2. Section 266(3): first adjust to fee: ₹30,000 − ₹5,000 = ₹25,000 left.
  3. Next adjust to interest: ₹25,000 − ₹4,000 = ₹21,000 left.
  4. The balance ₹21,000 goes to tax.
  5. Tax remaining = ₹50,000 − ₹21,000 = ₹29,000.

Answer: Fee ₹5,000 and interest ₹4,000 are cleared and ₹21,000 reduces the tax. ₹29,000 of tax remains unpaid, and Ravi is deemed an assessee in default for it (section 266(8)).

Exam tips

  • Quote section 266 by number in theory answers and give the three points: pay before filing, attach proof, and the fee-interest-tax order.
  • In numericals, show the credits as a list so you earn a mark for each one.
  • Write one closing line on section 266(7) and (8) in answers that mention assessment or default.
  • Use the terms tax year and Income-tax Act, 2025. Avoid assessment year.
  • In MCQs, check the order of adjustment carefully. Tax is last, not first.

Practice questions from Self-Assessment and Intimation

Self-Assessment of Tax and Payment Before Filing in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Self-Assessment of Tax and Payment Before Filing: frequently asked questions

When must self-assessment tax be paid?

You must pay it before furnishing the return. Section 266(1) also requires the return to be accompanied by proof of payment of the tax, interest and fee.

What credits reduce self-assessment tax?

Section 266(2) lists tax already paid, TDS and TCS, relief under section 157, foreign tax relief under sections 159 and 160, the specified tax credits in clause (f), and tax or interest payable under section 391(2).

If I pay less than what is due, where does the payment go?

Under section 266(3), it is adjusted first towards fee, then interest, and the balance towards tax. Any unpaid tax, interest or fee makes you an assessee in default.

Is the self-assessment payment lost if the case is assessed later?

No. Section 266(7) says that after a regular assessment under section 270 or 271 or an assessment under section 294, the amount paid is deemed paid towards that assessment.