Advance Tax and the 234B/234C Interest Traps
Sections 234B and 234C both charge interest at 1% per month on an advance-tax shortfall — which makes it tempting to treat them as one check. They're not. 234C tests whether each quarterly instalment was paid on schedule; 234B tests whether the year-end position cleared a single 90% bar. A taxpayer can breach one and not the other, in either direction.
When Advance Tax Applies at All
Under Sections 208/211, advance tax liability arises wherever estimated tax (after TDS/TCS credit) is ₹10,000 or more. Below that, none of what follows applies.
Section 234C: The Instalment Schedule
Regular assessees follow a four-instalment cumulative schedule:
| Due date | Cumulative % required |
|---|---|
| 15 June | 15% |
| 15 September | 45% |
| 15 December | 75% |
| 15 March | 100% |
Section 44AD/44ADA presumptive assessees get a simplified single-instalment schedule: 100% due by 15 March, nothing owed before that.
Interest under 234C runs at 1% per month on the shortfall at each instalment — but the exposure period differs by instalment: the first three checkpoints (June, September, December) each carry a 3-month interest window if missed, while the final March instalment (and the presumptive single instalment) carries just 1 month. Miss the June checkpoint by a wide margin and it costs three months of interest on that shortfall alone, even if the December and March instalments are both filed exactly on time and in full.
Section 234B: The Year-End 90% Bar
234B asks a completely different question: was advance tax paid by 31 March at least 90% of the assessed tax? If not, interest runs at 1% per month on the shortfall (assessed tax minus advance tax paid), starting 1 April of the assessment year and continuing until the date of actual payment — which can stretch well past the return-filing date if self-assessment tax is paid late.
This is where the two sections genuinely diverge from each other: 234C is checkpoint-based and forgives a mid-year miss if the final position corrects it, while 234B only cares about the single 31 March snapshot and then keeps accruing for as long as the shortfall remains unpaid.
Why Both Can Bite the Same Taxpayer, Independently
A taxpayer who paid nothing by June, caught up fully by December, and hit 100% by March has a real 234C exposure on the June and September shortfalls — interest that doesn't disappear just because the year ended clean. Meanwhile, a taxpayer who paid on schedule every quarter but under-estimated total tax, landing at 85% of the eventual assessed figure by 31 March, clears every 234C checkpoint but still owes 234B interest on the 5-percentage-point gap below the 90% bar, accruing from 1 April until whenever the balance is actually paid.
Neither section substitutes for the other. A clean 234C position says nothing about 234B exposure, and vice versa.
Frequently Asked Questions
If I pay 100% of my tax by 15 March, do I still owe 234C interest?
You can. 234C interest accrues at each checkpoint independently — a shortfall at the June or September instalment generates interest for that checkpoint's exposure window (3 months) even if the final 15 March instalment brings the cumulative position to 100%. Catching up at year-end doesn't retroactively erase an earlier checkpoint's shortfall.
What's different about the presumptive taxation (44AD/44ADA) instalment schedule?
Presumptive assessees skip the four-checkpoint schedule entirely and owe a single instalment — 100% by 15 March, with a 1-month interest exposure window if missed, rather than the regular assessee's staggered June/September/December/March checkpoints.
Does 234B interest stop accruing once the return is filed?
No. It continues from 1 April of the assessment year until the date the shortfall is actually paid — filing the return doesn't stop the clock if the tax itself, including self-assessment tax, remains outstanding.
Can I owe 234B interest even if every advance tax instalment was on time?
Yes, if the total amount paid by 31 March — even paid exactly on each 234C checkpoint — still falls short of 90% of the eventual assessed tax. 234C tests the schedule; 234B tests the year-end total against a different bar. A clean instalment record doesn't guarantee clearing 90%.
CORAA's Advance Tax & 234B/234C Calculator runs both tests off the same estimated-tax and payment inputs — the four-checkpoint 234C schedule (or the presumptive single instalment) and the 90%-by-31-March 234B test — so a clean position on one doesn't get mistaken for a clean position on both.