Advance Tax & Self-Assessment Tax: Dates, Interest (2026)

Salary earners have their tax deducted at source before the money ever reaches them. Everyone else — freelancers, investors, landlords, sellers of property or stock — is the tax department's own collection agent. Miss the rhythm and the law charges you interest for the privilege: 1% a month, compounding through the year. This post covers both halves of paying your own tax: advance tax during the year, self-assessment tax at filing, with the dates, the concessional routes, and the interest arithmetic that punishes drift.

Who owes advance tax, and when

Advance tax applies when your total tax liability after TDS crosses ₹10,000 in a financial year — salary TDS counts against the total, so a salaried person with a side income often still owes nothing in advance. Source: Income Tax Department, incometax.gov.in, as our IPO-tax and ITR guides cite. The instalment table (Income-tax Act, 1961, section 211, operative for AY 2026-27; the Income-tax Act, 2025 restates the same schedule from FY 2026-27 per our freelancer guide's verification):

Note the structure: each date is a cumulative floor, not a standalone slice. Paying 30% by September 15 means you are short of the 45% floor — 234C interest runs on the shortfall even though you "paid something". And capital gains count: sell stock or property in a quarter and the tax lands in that quarter's instalment, as our IPO-tax guide warns — brokers deduct nothing at source on gains.

The presumptive concession: one instalment, March 15

Presumptive taxpayers get the single most useful concession in this chapter: if your income is computed under the presumptive schemes — sections 44AD/44ADA of the 1961 Act for AY 2026-27, restated as Section 58 of the Income-tax Act, 2025 from FY 2026-27 — the entire advance tax can be paid as one instalment by March 15. Source: section 211's presumptive proviso, Income-tax Act, 1961; the 2025 Act restatement as verified in our freelancer guide. Paying on the quarterly table instead is perfectly fine — earlier instalments are never penalised — but a freelancer whose income lands late in the year can lawfully wait until March 15 without any 234C exposure. For professionals whose clients pay in 60–90 days, that concession is the difference between borrowing to pay tax and paying from collections.

The interest arithmetic that enforces it

Two sections police the table (operative AY 2026-27 numbers; the 2025 Act restates them with the same mechanics):

• Section 234C — 1% per month for each instalment shortfall, on the amount of the shortfall, for the months of default. Pay the December 15 floor in January and the interest runs on the missing slice.
• Section 234B — if advance tax paid by March 31 is less than 90% of the assessed tax, 1% per month runs from April 1 of the assessment year until the tax is actually paid. This is the interest that surprises filers: it starts before you even file, on the whole unpaid remainder.

Source: Income Tax Act interest provisions as summarised in our ITR critical-changes guide and on incometaxindia.gov.in. On a ₹2 lakh shortfall, each month of neglect costs about ₹2,000 — small enough to ignore, large enough to compound into five figures by September.

Self-assessment tax: the last payment before filing

By filing time the arithmetic is mechanical: total tax payable plus surcharge and cess, minus TDS, minus TCS, minus advance tax paid — what remains is self-assessment tax, payable before you submit the return. Miss it and section 234A adds its own 1% a month from the due date for late filing. Our ITR critical-changes guide states the full formula: Total Tax + Surcharge + Cess + Interest (234A/234B/234C) − TDS − TCS − Advance Tax − Reliefs = Self-Assessment Tax Payable. Pay it, note the challan identification number (CIN), and the return's tax schedule fills itself from it.

How to actually pay

The e-Pay Tax module on incometax.gov.in handles both. Pick the correct tax year, choose Advance Tax (challan type 100) or Self-Assessment Tax (type 300), and pay from net banking, debit card, or through the bank rails the portal lists. One transition-year trap, as our challan guide covers: from April 1, 2026, new challans under the Income-tax Act, 2025 apply to Tax Year 2026-27 — old challans cover only dues up to FY 2025-26. Paying your March 15 instalment on the wrong form is a reconciliation headache the portal will not fix for you.

The worked example, checked line by line

A freelancer with ₹60 lakh of gross receipts, 100% digital, electing presumptive taxation — the same profile our freelancer guide works: deemed income is 50%, i.e. ₹30 lakh. New-regime tax on ₹30 lakh: 5% of ₹4–8 lakh (₹20,000) + 10% of ₹8–12 lakh (₹40,000) + 15% of ₹12–16 lakh (₹60,000) + 20% of ₹16–20 lakh (₹80,000) + 25% of ₹20–24 lakh (₹1,00,000) + 30% of ₹24–30 lakh (₹1,80,000) = ₹4,80,000, plus 4% cess = ₹4,99,200. TDS collected: say ₹40,000 of 194J deductions. Advance tax due: ₹4,59,200.

On the quarterly table: ₹68,880 (15%) by June 15, ₹2,06,640 cumulative (45%) by September 15, ₹3,44,400 (75%) by December 15, ₹4,59,200 (100%) by March 15. Under the presumptive concession: the entire ₹4,59,200 by March 15, no 234C questions asked. Skip both, and 234B runs at 1% a month from April — about ₹4,600 a month on this balance — plus 234A if the return itself is late. Every number above is arithmetic you can check with a calculator and the slab table in our old-versus-new-regime post.

What goes wrong

The estimation habit that replaces the anxiety

The quarterly instalment only needs an estimate, and a fifteen-minute one is enough. Add up income earned since April 1 (salary slips, business receipts, redeemed gains), apply the slab table from our regime-comparison post, subtract TDS already deducted from Form 26AS, and the remainder times the cumulative percentage due is your instalment. Overestimate slightly — excess advance tax earns nothing back, but a small buffer beats a 234C shortfall by construction. Do this in the first week of June, September and December, from one saved spreadsheet, and the table above stops being a deadline you fear and becomes a transfer you schedule.

Two naming traps in the transition year

Filers this season meet three overlapping labels: assessment year (AY 2026-27), financial year (FY 2025-26) and the new "tax year" nomenclature the 2025 Act brings for the year after. The rule from our critical-changes guide: the return you file now covers income through March 31, 2026 and runs on the 1961 Act — 234B, 234C, 44AD and the rest of the section numbers above. The Income-tax Act, 2025 governs income from April 1, 2026, where the same mechanics carry new numbers (presumptive income sits in Section 58, and forms renumber — Form 16 to Form 130, Form 26AS to Form 168). When a challan or portal screen asks for the year, slow down for one second: the transition year's single most common filing error is paying or filing against the wrong year label.

• The rebate illusion. The new regime's 87A rebate clears tax up to ₹12 lakh of income — but as our salaried guide notes, the rebate does not cover tax on capital gains at special rates. A ₹9 lakh salary plus a ₹3 lakh equity gain still generates advance-tax liability on the gain's tax.
• One big gain, one missed quarter. Property or stock sold in Q3 puts the entire capital-gains tax into the December instalment — or triggers 234C at 1% monthly if it waits for March. Our capital-gains filing guide covers the rates; this post covers the calendar.
• Refunds as savings plans. Overpaying through the year and collecting a refund is lending the department money at zero — while refunds due to you earn only 6% a year under section 244A, and only when filed on time. Pay the accurate amount instead.
• Paying without the challan discipline. A self-assessment payment made but never entered against the right assessment year produces a phantom demand at filing. Keep every CIN; reconcile against Form 26AS (Form 168 from Tax Year 2026-27) before submitting.

The verdict

The system is simple once you see it as two clocks: the advance-tax clock runs quarterly during the year (or once, on March 15, if you are presumptive), and the self-assessment clock runs once, before filing. Estimate honestly each quarter — our ITR guides walk the computation — pay the floor that is due, and the interest sections never wake up. The tax itself is priced in our old-versus-new regime comparison; the filing mechanics, in our ITR guide; and the presumptive election that unlocks the March 15 concession, in our freelancer guide.

This is educational content, not investment advice. Consult a SEBI-registered advisor for decisions specific to your situation.