Income tax calculator: enter your yearly income and, for the old regime, your deductions. Both regimes are worked out side by side with the rebate, surcharge and 4% cess, and income and tax rounded to ₹10 as the law requires. Then add your filing date, TDS and advance tax to see the interest under 234A, 234B and 234C and the late fee under 234F (sections 423, 424, 425 and 428 from tax year 2026-27). Due dates for FY 2025-26: 31 July 2026 without business income, 31 August 2026 with business income, and 21 November 2026 (extended from 31 October) for audit cases; a late return is allowed until 31 December 2026. Resident individuals; capital gains and other special-rate income are not included.
Calculate your tax
Video: how to use the income tax calculator
Shown in the BooksOn HSN app; the steps are the same on this page: income, deductions, both regimes, TDS and the PDF report.
Filing date, interest and late fee
If you file after the due date, you pay a late fee and interest, and a late return must use the new regime. Choose your return type and the date you filed or plan to file; the tax comes from the calculator above.
If you miss the due date
What filing on time, late or very late means for you. Sections are given as 1961 Act · 2025 Act: the first for FY 2025-26, the second for tax year 2026-27.
Filed on time
- No late fee and no interest for filing late (234A · 423). Interest for short advance tax (234B, 234C · 424, 425) still applies if you paid too little advance tax.
- You may choose the old regime in the return; with business income, by filing Form 10-IEA by the due date (115BAC(6) · 202(4)).
- Losses can be carried forward to later years (139(3), 80 · 121).
- A refund earns interest of 0.5% a month from 1 April (244A · 437).
- You can correct mistakes with a revised return until 31 March 2027 (FY 2025-26) or 31 March 2028 (tax year 2026-27); a revision after 31 December costs ₹1,000 or ₹5,000 (234-I · 428(b)).
Late, but by 31 December
A late (belated) return can be filed until 31 December 2026 for FY 2025-26 and 31 December 2027 for tax year 2026-27 (139(4) · 263(4)).
- If you had to file: a flat late fee of ₹1,000 (total income up to ₹5 lakh) or ₹5,000 (234F · 428(a)).
- Interest of 1% a month on the tax still unpaid at the due date, up to the day you file. Tax paid by the due date carries no such interest (234A, Circular 2/2015 · 423).
- Only the new regime: 80C, 80D, HRA and home-loan interest are lost (115BAC(6) · 202(4)).
- Business, speculation and capital-gains losses cannot be carried forward; a house-property loss still can (80 · 121).
- For FY 2025-26, deductions such as 80QQB, 80RRB and 80JJAA are also lost (80AC).
- Refund interest runs only from the date you file (244A · 437).
- Once you file, there is no prosecution for not filing (276CC proviso · 479(2)).
After 31 December: updated return only
- Only an updated return (ITR-U) is possible: until 31 March 2031 for FY 2025-26 and 31 March 2032 for tax year 2026-27. You pay the tax, interest and late fee, plus additional tax of 25% of the tax and interest (up to 31 March 2028 for FY 2025-26; 31 March 2029 for tax year 2026-27), then 50%, 60% and 70% in the following years (139(8A), 140B · 263(6), 267).
- An updated return cannot show a loss, lower the tax or claim a refund. It is not allowed after a search or survey, or while an assessment is pending.
- If a refund is due, the only way left is to ask the tax department to condone the delay (119(2)(b)).
- If you filed a return earlier (on time or late), it can still be corrected with a revised return until 31 March 2027 for FY 2025-26 and 31 March 2028 for tax year 2026-27: a fee of ₹1,000 (total income up to ₹5 lakh) or ₹5,000, and no additional tax (139(5), 234-I · 263(5), 428(b)).
Never filing
- The department can assess your income itself (144 · 271), and interest for filing late runs until it does.
- Penalty: 50% of the tax on income above the exemption limit, or 200% if income was misreported (270A · 439).
- Prosecution for wilful failure only: if the tax evaded is up to ₹10 lakh, a fine only; ₹10 lakh to ₹50 lakh, simple imprisonment up to 6 months, a fine or both; above ₹50 lakh, up to 2 years. None if the net tax is ₹10,000 or less, or if an updated return is filed (276CC · 479).
Due dates and key dates
| FY 2025-26 (return in 2026) | Tax year 2026-27 (return in 2027) | |
|---|---|---|
| No business income: salary, pension, rent, interest | 31 Jul 2026 | 31 Jul 2027 |
| Business or profession, no audit (including 44AD and 44ADA) | 31 Aug 2026 | 31 Aug 2027 |
| Accounts audited | 31 Oct 2026, extended to 21 Nov 2026 | 31 Oct 2027 |
| Late (belated) return, last date | 31 Dec 2026 | 31 Dec 2027 |
| Revised return, last date (fee after 31 Dec) | 31 Mar 2027 | 31 Mar 2028 |
| Updated return at 25% / 50% / 60% / 70% additional tax, up to 31 Mar | 2028 / 2029 / 2030 / 2031 | 2029 / 2030 / 2031 / 2032 |
| Advance tax: 15%, 45%, 75%, 100% by | 15 Jun, 15 Sep, 15 Dec 2025, 15 Mar 2026 | 15 Jun, 15 Sep, 15 Dec 2026, 15 Mar 2027 |
| Interest for short advance tax counted from | 1 Apr 2026 | 1 Apr 2027 |
| Sections | 139, 140B; 234A, 234B, 234C, 234F (Income-tax Act, 1961) | 263, 267; 423, 424, 425, 428 (Income-tax Act, 2025) |
Due dates: section 139(1) Explanation 2 as replaced by the Finance Act, 2026, and section 263(1)(c) of the Income-tax Act, 2025. The 21 November 2026 date is from CBDT Circular 07/2026 dated 28 September 2026, for audit cases only. Transfer-pricing cases (30 November) are not covered here.
How the interest and fee are worked out
- Months: any part of a month counts as a full month, and the amount is rounded down to the nearest ₹100 (Rule 119A · Rule 269). Due 31 July, filed 9 December: 5 months.
- Filing late (234A · 423): 1% a month on the tax unpaid at the due date (after TDS, advance tax and self-assessment tax paid by the due date), from the day after the due date to the day you file.
- Short advance tax (234B · 424): if advance tax paid by 31 March is less than 90% of the tax after TDS, 1% a month on the shortfall from 1 April to the day you pay. Tax paid earlier stops the interest on that part.
- Late instalments (234C · 425): 3% on the shortfall at 15 June (15% due; nothing if 12% was paid), 15 September (45%; nothing if 36% was paid) and 15 December (75%), and 1% on the shortfall at 15 March (100%). Presumptive income (44AD, 44ADA): only the 15 March instalment. Tax paid from 16 to 31 March counts for 234B only.
- No advance tax, so no 234B or 234C: residents aged 60 or more without business income, and anyone whose tax after TDS is under ₹10,000 (207(2), 208 · 403(3), 404).
- Late fee (234F · 428(a)): ₹1,000 if total income is up to ₹5 lakh, otherwise ₹5,000, only if you had to file. It is flat: it does not grow with the delay.
- Updated return (140B · 267): additional tax of 25%, 50%, 60% or 70% of the tax and interest, by how late it is. No interest is charged on the additional tax.
- Total: rounded to the nearest ₹10 (288B · 516).
Example: salary ₹14,75,000, TDS ₹80,000, no advance tax, due 31 July 2026, filed 15 November 2026. New regime tax ₹93,600, so ₹13,600 is unpaid. 234A: ₹13,600 × 1% × 4 months = ₹544. 234B: ₹13,600 × 1% × 8 months = ₹1,088. 234C: ₹60 + ₹183 + ₹306 + ₹136 = ₹685. Late fee ₹5,000. Total ₹20,917, so you pay ₹20,920. Filed by 31 July, the same person would have paid ₹14,829, rounded to ₹14,830: being late costs ₹6,088 more before rounding (₹20,917 − ₹14,829), or ₹6,090 in the rounded amounts.
Points not yet confirmed
- Audit cases, FY 2025-26: Circular 07/2026 moves the due date to 21 November 2026 but does not say whether interest and the fee start after 31 October or after 21 November. The calculator uses 21 November (you can choose the official date instead). Paying the tax by 31 October 2026 removes the doubt. How months are counted from 22 November (22nd to 21st, as here, or by calendar month) is also not confirmed.
- Whether Form 10-IEA filed by the due date keeps the old regime when the return itself is late.
- The ₹4 lakh limit (new regime) as the income above which you must file: widely used, but not stated in an official FAQ.
- Whether the late fee can simply reduce a refund in the return.
- The wording of the revised-return fee (234-I) for FY 2025-26.
- Whether someone who never filed can file an updated return between 1 January and 31 March.
- Tax year 2026-27: the wording of section 425(2) (the 12% and 36% limits), the part-month rule in section 423 and the new-regime rule for late returns (section 202(4)). Official FAQs are awaited.
- Cess is included in the tax on which interest is charged, as in the department's examples; each interest amount is in whole rupees and only the total is rounded to ₹10.
- If an advance tax date falls on a bank holiday, the department’s FAQ treats a payment on the next working day as on time, and the calculator follows it; this is not confirmed (15 June 2025 and 15 March 2026 were Sundays).
Sources (incometaxindia.gov.in): Income-tax Act, 1961 sections 139, 234A, 234B, 234C, 234F, 140B, 115BAC and Rule 119A; Income-tax Act, 2025 sections 263, 423, 424, 425, 428, 267, 479 and Rule 269; CBDT Circular 07/2026; FAQs on interest under sections 423 to 426.
New regime tax slabs, FY 2025-26 and 2026-27
The default regime. One table for every age; standard deduction ₹75,000 on salary or pension; rebate up to ₹60,000 when taxable income is up to ₹12 lakh, with marginal relief just above it.
| Taxable income | Rate |
|---|---|
| Up to ₹4,00,000 | Nil |
| ₹4,00,001 to ₹8,00,000 | 5% |
| ₹8,00,001 to ₹12,00,000 | 10% |
| ₹12,00,001 to ₹16,00,000 | 15% |
| ₹16,00,001 to ₹20,00,000 | 20% |
| ₹20,00,001 to ₹24,00,000 | 25% |
| Above ₹24,00,000 | 30% |
Old regime tax slabs
Standard deduction ₹50,000; rebate up to ₹12,500 when taxable income is up to ₹5 lakh (no marginal relief).
| Taxable income | Below 60 | 60 to 79 | 80 or more |
|---|---|---|---|
| Up to ₹2,50,000 | Nil | Nil | Nil |
| ₹2,50,001 to ₹3,00,000 | 5% | Nil | Nil |
| ₹3,00,001 to ₹5,00,000 | 5% | 5% | Nil |
| ₹5,00,001 to ₹10,00,000 | 20% | 20% | 20% |
| Above ₹10,00,000 | 30% | 30% | 30% |
Both regimes add 4% health and education cess on the tax. Surcharge applies above ₹50 lakh (10%), ₹1 crore (15%) and ₹2 crore (25%); the old regime adds 37% above ₹5 crore, while the new regime stops at 25%. Marginal relief keeps the extra tax from exceeding the extra income at each threshold.
Example: ₹15 lakh salary
New regime: ₹15,00,000 − ₹75,000 standard deduction = ₹14,25,000 taxable. Slab tax ₹93,750 + 4% cess = ₹97,500. The old regime costs less only if your old-regime deductions (HRA, 80C, 80D, home-loan interest and the rest) add up to more than about ₹5.44 lakh.
More in the BooksOn HSN app
- PDF report of both regimes to download or share with your employer or CA.
- HRA calculator: the exempt HRA from basic + DA, HRA received and rent paid, with the 50% cities for each year (eight from 2026-27).
- Advance tax plan: what to pay by 15 June, September, December and March after TDS.
- Presumptive income for business (44AD) and profession (44ADA), employer NPS, and tips on the deductions you have room for.
- Filing date, interest and late fee (version 1.0.4): the same due dates, interest under 234A, 234B and 234C and late fee as on this page, with the official, extended or your own due date.
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Questions
What is the last date to file the income tax return for FY 2025-26?
31 July 2026 if you have no business income; 31 August 2026 with business or professional income and no audit (a new date from the Finance Act, 2026); 31 October 2026 for audit cases, extended to 21 November 2026 by CBDT Circular 07/2026. After that, a late (belated) return can be filed until 31 December 2026. For tax year 2026-27 the dates are 31 July, 31 August and 31 October 2027.
What is the late fee for filing the income tax return late?
₹5,000, or ₹1,000 if total income is up to ₹5 lakh (section 234F; section 428(a) from tax year 2026-27). It is a flat fee that does not grow with the delay, and there is none if you were not required to file. Interest on any unpaid tax comes on top.
How is interest under 234A, 234B and 234C worked out?
At 1% a month, where any part of a month counts as a full month and the amount is rounded down to ₹100. 234A: on tax unpaid at the due date, from the next day until you file. 234B: if advance tax paid by 31 March was below 90% of the tax, on the shortfall from 1 April until you pay. 234C: 3% on each short instalment at 15 June (15%), 15 September (45%) and 15 December (75%), and 1% on the shortfall at 15 March. Example: ₹13,600 unpaid, due 31 July 2026, filed 15 November 2026: 234A ₹544, 234B ₹1,088, 234C ₹685, plus the ₹5,000 fee.
Can I choose the old regime if I file the return late?
Generally no. The old regime can be chosen only in a return filed by the due date (with business income, by filing Form 10-IEA by the due date). A late return is taxed under the new regime, so 80C, 80D, HRA and home-loan interest are lost.
What if I miss 31 December too?
Then only an updated return (ITR-U) is possible, until 31 March 2031 for FY 2025-26. You pay the tax, interest, the late fee and additional tax of 25% of the tax and interest, rising to 50%, 60% and 70% in later years. An updated return cannot claim a refund or show a loss.
Is income up to ₹12 lakh tax-free in the new regime?
Yes. In the new regime, a resident individual with taxable income up to ₹12,00,000 pays no tax because of the rebate of up to ₹60,000. With the ₹75,000 standard deduction, a salary up to ₹12,75,000 pays no tax. Just above ₹12 lakh, marginal relief limits the tax to the income above ₹12 lakh.
What are the new regime tax slabs for FY 2025-26?
Up to ₹4 lakh: nil; ₹4–8 lakh: 5%; ₹8–12 lakh: 10%; ₹12–16 lakh: 15%; ₹16–20 lakh: 20%; ₹20–24 lakh: 25%; above ₹24 lakh: 30%. The same slabs apply for every age, plus 4% health and education cess. The Finance Act, 2026 kept them for tax year 2026-27.
Which is better, the old or the new tax regime?
It depends on your deductions. The new regime has lower rates and a ₹75,000 standard deduction but allows few other deductions; the old regime allows 80C, 80D, HRA and home-loan interest. For a ₹15 lakh salary, the new regime's tax is ₹97,500, and the old regime costs less only with old-regime deductions above about ₹5.44 lakh.
What is the standard deduction for salaried people?
₹75,000 in the new regime and ₹50,000 in the old regime, on salary or pension, for FY 2025-26 and tax year 2026-27.
What changed with the Income-tax Act, 2025?
From 1 April 2026 the Income-tax Act, 2025 replaces the 1961 Act and "previous year" and "assessment year" become one "tax year". The new regime is section 202, the rebate section 156 and the standard deduction section 19; the Finance Act, 2026 kept the 2025 slabs, rebate and deduction limits. HRA's 50% cities grew from four (Delhi, Mumbai, Kolkata, Chennai) to eight, adding Bengaluru, Hyderabad, Pune and Ahmedabad. Interest for late returns and short advance tax moved to sections 423, 424 and 425, and the late fee to section 428, at the same rates.
Reference only, not tax advice: confirm with the Income-tax Act and your CA before filing. Slab figures from the Finance Act, 2025 and the Income-tax Act, 2025 as used in the BooksOn HSN app; due dates, interest and fee from the sections and CBDT papers listed above.
