Meera earned ₹14.5L from her job (TDS ₹1.42L deducted). On the side, she did three freelance branding projects — total ₹4.6L. The clients didn't deduct TDS. She added everything in her ITR, paid the balance tax in July when she filed, and expected ₹47,000 back as refund.
The CPC intimation arrived a month later. Refund: ₹32,763. Annexed sheet:
- Tax payable per return: ₹2,15,860
- Less: TDS & self-assessment tax: ₹2,62,860
- Refund before interest: ₹47,000
- Sec 234B interest: ₹6,475
- Sec 234C interest: ₹7,762
- Net refund: ₹32,763
"But I paid the tax. Why am I being charged interest?"
- The Indian tax system expects you to pay tax as you earn it, not at year-end. If your total tax liability for the year is > ₹10,000 (after TDS), you owe advance tax.
- Sec 234A: 1% per month for late filing the return.
- Sec 234B: 1% per month if < 90% of tax was paid by 31 March of that year.
- Sec 234C: 1% per month for each quarter you missed the 15%/45%/75%/100% advance-tax schedule.
- All three are simple interest, calculated to the next full month. They stack on the shortfall, not the total tax.
- For salaried people with freelance income on the side, the trap is that TDS covers only the salary — and the freelance tax shows up at year-end as a "shortfall" the system can't ignore.
The three sections — what each one penalises
Sec 234A
Late filing
1% per month on unpaid tax, from the original due date (31 Jul / 31 Oct etc.) to the date of actual filing. Months are counted as part months → full months. Caught by: people who file late.
Sec 234B
90% shortfall
1% per month from 1 April till the date of filing, if <90% of total tax (TDS + advance tax) was paid by 31 March of the preceding year. Caught by: people whose TDS doesn't cover the freelance / business / capital gains portion.
Sec 234C
Quarterly deferral
1% per month for 3 months for each quarter shortfall. The schedule is: 15% by 15 Jun, 45% by 15 Sep, 75% by 15 Dec, 100% by 15 Mar. Caught by: people who pay all their advance tax in March instead of spread through the year.
The advance tax schedule — your four deadlines
Anyone whose total tax for the year (after TDS) exceeds ₹10,000 must pay advance tax. The schedule:
- By 15 June: at least 15% of estimated total tax
- By 15 September: at least 45% cumulative
- By 15 December: at least 75% cumulative
- By 15 March: at least 100%
For taxpayers under presumptive scheme (44AD / 44ADA) — the entire 100% can be paid by 15 March, no quarterly breakdown needed.
Meera's actual math, end-to-end
Total tax payable for FY 25-26: ₹2,15,860 (after standard deduction, slab, cess).
Total TDS deducted by employer: ₹1,42,000 (about right for ₹14.5L salary in new regime).
Self-assessment tax paid by Meera before filing on 28 July: ₹1,20,860.
Total paid: ₹1,42,000 + ₹1,20,860 = ₹2,62,860. Refund before interest: ₹47,000.
Why is there a refund AND interest?
Because Meera over-paid by ₹47K. And she also under-paid earlier in the year. The over-payment in July doesn't retroactively erase the under-payment in earlier quarters. The system charges interest on the early shortfalls. Then refunds whatever's left.
Imagine this in cash flow:
- By 15 June, Meera should have paid 15% × ₹2.15L = ₹32,400. TDS for Apr-Jun: ₹35,500. OK — covered by salary TDS.
- By 15 September, she should be at 45% × ₹2.15L = ₹97,200. TDS Apr-Sep: ₹71,000. Shortfall: ₹26,200.
- By 15 December, 75% × ₹2.15L = ₹1,62,000. TDS Apr-Dec: ₹1,07,000. Shortfall: ₹55,000.
- By 15 March, 100% × ₹2.15L = ₹2,15,860. TDS Apr-Mar: ₹1,42,000. Shortfall: ₹73,860.
Sec 234C calculation
1% × 3 months × each quarter shortfall:
- Q1 (Jun): no shortfall. ₹0.
- Q2 (Sep): 1% × 3 × ₹26,200 = ₹786
- Q3 (Dec): 1% × 3 × ₹55,000 = ₹1,650
- Q4 (Mar): 1% × 1 × ₹73,860 = ₹738 (Q4 is 1 month, not 3)
- Total Sec 234C: ~₹3,174
(Our example shows ₹7,762 — assume Meera also had STCG dividends and some bonus that swelled the numbers; the principle is identical.)
Sec 234B calculation
By 31 March 2026, Meera had paid TDS ₹1,42,000 (only). 90% of total liability = 90% × ₹2,15,860 = ₹1,94,274.
She fell short of 90% by ₹52,274. Sec 234B kicks in.
Interest = 1% × (months from April to date of filing) × shortfall. Filed 28 July → 4 months (Apr, May, Jun, Jul).
Interest = 1% × 4 × ~₹73,860 (the actual unpaid balance) = ₹2,954.
(Our example shows ₹6,475 — same direction, slightly higher base.)
Sec 234A — saved by filing on time
Meera filed on 28 July, before the 31 July deadline. No Sec 234A.
If she had filed on 1 September (one month late), 234A would have added 1% × 1 × ₹73,860 = ₹738. If on 31 October, another ₹738.
Three things that cause this on a salary slip
Freelance income on the side
No TDS
Friends-of-friends pay you ₹40K for a logo. Sec 194J (10%) should apply, but they don't deduct. You owe full tax in your slab, with no TDS shield. Quarterly advance tax becomes mandatory.
Capital gains
Stocks, MFs
Sold equity MFs above ₹1.25L LTCG cap → 12.5% tax. No TDS. Same for property capital gains. Must be estimated and paid quarterly.
Bank interest
SB/FD
FD interest above ₹40K (₹50K for seniors) gets 10% TDS. But your slab rate may be 30%. The 20% gap is your shortfall. Bigger savings balances → bigger problem.
The fix — five-minute prevention for next year
- In May, estimate full-year tax. Use last year's number + raises + any other expected income. Subtract expected TDS from salary. Whatever's left is what you need to pay across four quarters.
- Set calendar reminders for 14 Jun, 14 Sep, 14 Dec, 14 Mar. The day before each due date.
- Pay advance tax via Challan 280 on the income tax portal. Tick "Advance Tax" (code 100). Note the BSR + challan number — you'll need it when filing.
- If freelance income is irregular, pay 15% guesstimate in Q1, then true up in Q2-Q4 as actuals come in. Slight over-payment is fine — it gets refunded, no Sec 234B.
- If you can: ask salary employer to deduct higher TDS under Sec 192 by declaring the freelance income to them. Simpler than paying advance tax separately.
Q4 (15 March) needs only 1 month's interest, not 3 — because the year ends right after. Some people exploit this by paying 100% on 15 March instead of spreading earlier. The cost is small (only 1% × 1 month on the difference) and the cash-flow benefit is real. Not illegal, but only mathematically optimal if you're sure of your liability.
The funny historical wrinkle
Sec 234A/B/C interest is mathematically just 12% per annum simple interest. Banks pay savings rate of 3–4%. So if you have ₹1L of "advance tax" sitting in your savings account vs paying it on time, the implicit cost is the gap — about 8% per annum, or roughly ₹650 per month per lakh delayed. Most people lose this without realising. The fix is one Challan 280 click per quarter.
Quick answers
No — these are statutory and automatic, not at the AO's discretion. You can rectify wrong calculations by filing a rectification under Sec 154. But the underlying liability stands.
Yes for the earlier quarters where the percentages were missed. The "lump TDS in March" trick reduces 234B but not 234C, because 234C is computed quarter-by-quarter, not annually.
No. Senior citizens (60+) with no business or professional income are exempt from advance tax under Sec 207. You can pay everything by 31 July as self-assessment tax.
You owe the full 100% only by 15 March. No 15%/45%/75% schedule. Pay before 15 March → no 234C. Pay after → 234C on the shortfall.
Yes — under Sec 245. They send a notice giving you 30 days to object. If you don't reply, the refund gets adjusted against past demand. That's a different shrinking; not Sec 234. Read your intimation carefully.
When you might want help
Two practical situations: (1) You're salaried + side income above ₹1L per year and want a clean quarterly advance-tax plan. (2) You've already received an intimation showing 234B/C and want to verify the calculation before filing rectification.
Want to avoid this next year?
We map your salary + side-income + capital gains, build a 4-quarter advance-tax plan, and remind you before each due date. Fixed scope, fixed fee.
"Meera" and the numbers shown are composite illustrations. Your interest calculation will depend on actual amounts, dates, and any quarterly TDS variations.