When your Income Tax Return shows an unexpected “Interest Payable” line, it is almost always one (or more) of four sections at work: 234A, 234B, 234C and 234F. Each has its own trigger, its own clock and its own math — but they all share one rate: 1% simple interest per month or part of a month. This framework continues unchanged in substance under the new Income Tax Act, 2025 (536 sections, effective 1 April 2026), so understanding it now protects you under both laws.
By the numbers: Interest under Sections 234A, 234B and 234C runs at 1% per month or part of a month — even a single day’s delay costs a full month’s interest — and the Section 234F late-filing fee is a flat ₹5,000 (₹1,000 if total income is ≤ ₹5 lakh). Source: Income Tax Department.
The four charges at a glance
| Section | Trigger | Rate / Amount |
|---|---|---|
| 234A | Filing your ITR after the due date | 1% per month on unpaid tax |
| 234B | Advance tax paid < 90% of assessed tax by 31 March | 1% per month on the shortfall, from 1 April |
| 234C | Missing the quarterly advance-tax cut-offs | 1% per month on each installment shortfall |
| 234F | Late filing (flat fee, not interest) | ₹5,000 (₹1,000 if income ≤ ₹5 lakh) |
“234B and 234C are the silent killers — most salaried filers never see them coming because their TDS lands in March. Pay your quarterly installments on time and both simply vanish.” — CA Juber Attar, TaxFetch e-CA Tax Expert
Section 234A: What happens when you file your ITR late?
Section 234A is the interest for delay in filing your return beyond the official due date (usually 31 July for individuals).
- Trigger: filing after the due date with tax still unpaid.
- Rate: 1% per month or part of a month — filing even one day into a new month counts as a full month.
- Applicable amount: assessed tax minus advance tax, TDS/TCS and any relief already claimed.
- Duration: from the day immediately after the due date until the actual filing date.
The good news: file on or before the deadline and 234A is always ₹0 — no matter how much tax you still owe at filing time.
Section 234B: What is the 90% advance tax rule?
Section 234B punishes a default in payment of advance tax for the year as a whole.
- Trigger: you paid less than 90% of your total assessed tax as advance tax (including TDS/TCS credit) by 31 March of the financial year. It applies only when your net outstanding tax is ₹10,000 or more.
- Rate: 1% per month or part of a month.
- Applicable amount: the shortfall — assessed tax minus advance tax/TDS already paid.
- Duration: from 1 April of the assessment year until the date you finally determine and pay the tax. Every month you delay filing and paying adds another 1%.
Section 234C: How do the quarterly advance tax deadlines work?
While 234B looks at the year as a whole, Section 234C checks each quarter separately. Advance tax must be deposited progressively through the year:
| Cut-off date | Cumulative advance tax required | Interest period if short |
|---|---|---|
| 15 June | At least 15% of total tax liability | 1% × shortfall × 3 months |
| 15 September | At least 45% | 1% × shortfall × 3 months |
| 15 December | At least 75% | 1% × shortfall × 3 months |
| 15 March | 100% | 1% × shortfall × 1 month |
The durations are hardcoded — 3 months for each of the first three installments and 1 month for the March installment — regardless of when you eventually pay. This is why income that arrives late in the year (a March bonus, TDS credited in Q4, a February capital gain) so often produces a 234C charge even for otherwise punctual taxpayers.
Section 234F and 234I: What are the flat late-filing fees?
- Section 234F is a flat fee, not interest: ₹5,000 if you file after the deadline, restricted to ₹1,000 when total income is under ₹5 lakh. It applies on top of any 234A interest.
- Section 234I covers fees connected with specific updated / revised return filings — relevant when you go back and correct a return under the updated-return framework.
File within the timeline and both are ₹0.
Worked example: how ₹9,120 of 234B and ₹11,514 of 234C get computed
Take a real portal-style computation for a taxpayer whose TDS landed late in the year:
| Item | Amount |
|---|---|
| Net tax liability (assessed tax) | ₹13,28,472 |
| Tax already paid (TDS) | ₹11,00,432 |
| Unpaid shortfall | ₹2,28,040 |
| Interest u/s 234B | ₹9,120 |
| Interest u/s 234C | ₹11,514 |
| Total amount payable | ₹2,48,670 (approx. shortfall + interest) |
Step 1 — Verifying the 234B interest of ₹9,120
- The unpaid amount is ₹13,28,472 − ₹11,00,432 = ₹2,28,040. Since this exceeds ₹10,000, Section 234B applies.
- Rule 119A rounding: before computing interest, the base is rounded down to the nearest multiple of ₹100 — so ₹2,28,040 becomes ₹2,28,000.
- Interest per month = 1% × ₹2,28,000 = ₹2,280.
- ₹2,280 × 4 months (April through July, counting the filing month as a full month) = ₹9,120. The portal figure reconciles exactly.
Step 2 — Verifying the 234C interest of ₹11,514
234C looks at the actual timestamps of your deposits. In this case the bulk of the ₹11,00,432 was credited as TDS in March, at the very end of the financial year — so the portal found shortfalls at the earlier cut-offs:
- 15 June: did cumulative payments reach 15% of ₹13,28,472? Shortfall → 1% × shortfall × 3 months.
- 15 September: reached 45%? Shortfall → 1% × shortfall × 3 months.
- 15 December: reached 75%? Shortfall → 1% × shortfall × 3 months.
- 15 March: reached 100%? Shortfall → 1% × shortfall × 1 month.
The four quarter-wise charges (each on its Rule 119A–rounded shortfall) total ₹11,514. The lesson: even when your total tax paid looks healthy, paying it late in the year still triggers 234C — the section cares about when, not just how much.
How do you avoid every one of these charges?
- File on time — kills 234A and 234F instantly.
- Hit 90% by 31 March — if TDS will not cover 90% of your assessed tax, pay the balance as advance tax before the year ends to avoid 234B.
- Pay quarterly, not annually — track the 15%/45%/75%/100% cut-offs (15 June / 15 Sep / 15 Dec / 15 Mar) to keep 234C at zero. Salaried taxpayers with rental, interest, capital-gains or freelance income are the most common victims.
- Remember “part of a month” — paying on the 2nd of a month costs the same interest as paying on the 30th. If a deadline slips, clear the dues at the start of the next month, not the end.
Frequently asked questions
Can 234A, 234B and 234C all apply at the same time?
Yes. They are independent charges — a taxpayer who underpays advance tax through the year and files late can be charged under all three, plus the flat 234F fee.
Is TDS counted as advance tax for these calculations?
Yes — TDS and TCS credits reduce your assessed tax for 234A and 234B. But for 234C the portal checks when amounts were actually credited against each quarterly cut-off, so TDS that lands only in March can still leave earlier installments short.
What is Rule 119A rounding?
Before computing interest, the principal is rounded down to the nearest multiple of ₹100 — e.g. a shortfall of ₹2,28,040 is treated as ₹2,28,000. It always works slightly in your favour.
Does one day’s delay really cost a full month of interest?
Yes. All three sections charge for a “month or part of a month” — crossing a deadline by even one day adds a complete month’s 1%.
Do these sections continue under the new Income Tax Act, 2025?
Yes — the new Act (effective 1 April 2026) carries forward the same interest-and-fee framework: 1% per month for late filing, advance-tax default and quarterly deferment, and the flat late-filing fee structure.
Key takeaways
- All three interest sections run at 1% simple interest per month or part of a month — there is no compounding, but no daily proration either.
- 234A = late filing; 234B = under 90% advance tax by 31 March; 234C = missing the quarterly 15/45/75/100 cut-offs; 234F = flat ₹5,000/₹1,000 late fee.
- Rule 119A rounds the interest base down to the nearest ₹100.
- 234C is timing-based — income or TDS arriving in March routinely triggers it even when the full tax is eventually paid.
- On-time quarterly payments + on-time filing = all four charges are ₹0.
Not sure whether your return will attract interest? Compute your full liability — including regime comparison and payable/refund position — with the free TaxFetch Income Tax Calculator, or get your Form 26AS TDS credits verified in minutes with TDS Fetch.
