Self Assessment Tax: Meaning, Calculation and How to Pay
If you are filing your ITR for FY 2025-26 and your tax liability after deducting TDS and advance tax is still showing a positive balance, that remaining amount is called self assessment tax. You must pay it before you submit your return. Skipping this step or paying it after the due date can attract interest under Sections 234A and 234B.
In my 7 years of working with salaried professionals and freelancers on their tax filings, I see this one step cause the most avoidable notices and demand orders. The calculation is straightforward once you know where to look. This guide walks you through exactly what self assessment tax is, how to calculate it, how it differs from advance tax, and the step-by-step process to pay it on the income tax portal.
What Is Self Assessment Tax?
Self assessment tax is the tax you pay on your own after the financial year ends, just before filing your ITR. It covers any income tax that was not collected through TDS by your employer or bank, or paid by you as advance tax during the year.
The Income Tax Department expects most of your tax to be paid during the year itself, either through TDS on salary or through advance tax instalments. If there is still a gap when you sit down to file your return, that gap is your self assessment tax liability.
Under the Income Tax Act 1961 (applicable for FY 2025-26 filing), self assessment tax is governed by Section 140A. You are required to calculate the tax yourself and pay it before submitting your ITR. This is exactly where the term “self assessment” comes from.
Self Assessment Tax vs Advance Tax: Key Difference
These two get confused often, and the confusion leads to wrong challan selection on the portal. Here is how they are different:
| Parameter | Advance Tax | Self Assessment Tax |
|---|---|---|
| When is it paid? | During the financial year (in 4 instalments) | After the financial year ends, before ITR filing |
| Who pays it? | Anyone with tax liability above Rs. 10,000 | Anyone with balance tax due at ITR time |
| Applicable period | April to March of the same FY | April onwards (after FY ends) |
| Challan type | ITNS 280, Type: (100) Advance Tax | ITNS 280, Type: (300) Self Assessment Tax |
| Interest on non-payment | Section 234B and 234C | Section 234A if paid after ITR due date |
If you missed advance tax payments during FY 2025-26, your self assessment tax liability will be higher because Section 234B interest gets added on top. You can read more about advance tax payment rules and instalments here.
Who Needs to Pay Self Assessment Tax?
You need to pay self assessment tax before filing your ITR if:
- Your total tax liability for FY 2025-26 is more than zero
- The TDS already deducted by your employer or bank does not cover your full tax liability
- You did not pay sufficient advance tax during the year
This applies more often than people expect. Salaried employees who earned income from other sources such as fixed deposit interest, freelance work, rental income, or capital gains frequently find a balance due because TDS on those sources was either lower than required or not deducted at all.
Example: Priya earns Rs. 14 lakh salary annually. Her employer deducted TDS of Rs. 98,000. She also earned Rs. 80,000 from fixed deposit interest on which TDS of Rs. 8,000 was deducted. Her total tax liability works out to Rs. 1,20,000. After accounting for total TDS of Rs. 1,06,000, she still owes Rs. 14,000. This Rs. 14,000 is her self assessment tax, and she must pay it before filing her ITR.
How to Calculate Self Assessment Tax
Follow this sequence to arrive at your self assessment tax amount:
Step 1: Calculate your gross total income Add all income heads: salary, house property, capital gains, other sources such as interest and dividends.
Step 2: Apply deductions Subtract eligible deductions under Section 80C, 80D, HRA exemption, and the standard deduction of Rs. 75,000 under the new regime or Rs. 50,000 under the old regime.
Step 3: Calculate income tax on net taxable income Apply the applicable slab rates for FY 2025-26. Under the new regime, income up to Rs. 12 lakh is effectively nil after the Section 87A rebate.
Step 4: Add 4% health and education cess Cess is added on the income tax figure, not on total income.
Step 5: Subtract TDS and advance tax already paid Cross-check your Form 26AS and AIS on the portal to confirm TDS amounts. Subtract both TDS and any advance tax paid during the year.
Step 6: Add interest for short payment if applicable If advance tax was not paid or was insufficient, add interest under Section 234B at 1% per month on the unpaid advance tax from April 1 to the date of actual payment.
The remaining amount after all these steps is your self assessment tax.
Practical Example:
| Particulars | Amount |
|---|---|
| Total income tax liability | Rs. 1,45,000 |
| Add: 4% health and education cess | Rs. 5,800 |
| Total tax + cess | Rs. 1,50,800 |
| Less: TDS deducted (as per Form 26AS) | Rs. 1,25,000 |
| Less: Advance tax paid | Rs. 10,000 |
| Add: Interest under Section 234B | Rs. 1,900 |
| Self Assessment Tax Payable | Rs. 17,700 |
Interest on Non-Payment: Section 234A and 234B
Delaying or skipping self assessment tax carries a direct cost in the form of interest, and it shows up as a demand notice after your return is processed.
Section 234B applies when your total advance tax payments during the year were less than 90% of your assessed tax liability. Interest is charged at 1% per month (or part of the month) on the shortfall from April 1 of the assessment year until the date of actual payment. This interest must be included in your self assessment tax payment itself.
Section 234A applies when tax remains unpaid beyond the ITR due date. Interest is charged at 1% per month on the outstanding self assessment tax from July 31, 2026 onwards. If you pay your self assessment tax before filing and before the deadline, Section 234A does not apply at all.
The ITR filing deadline for FY 2025-26 is July 31, 2026 for salaried individuals filing ITR-1 and ITR-2. Paying your self assessment tax before this date eliminates Section 234A interest entirely.
How to Pay Self Assessment Tax Online (Step-by-Step)
Self assessment tax is paid on the income tax e-filing portal using Challan ITNS 280. Here is the exact process:
Step 1: Go to incometax.gov.in and log in with your PAN and password.
Step 2: Navigate to e-Pay Tax under the Quick Links section or the e-File menu.
Step 3: Click on New Payment and select Income Tax as the tax applicable.
Step 4: Under the payment type, select (300) Self Assessment Tax. This is the step where most errors happen. Do not select Advance Tax (100) or Regular Assessment Tax (400).
Step 5: Fill in the Assessment Year. For FY 2025-26 income, select AY 2026-27.
Step 6: Enter the tax amount and the interest amount (Section 234B if applicable) in the respective fields. These are separate fields on the challan.
Step 7: Choose your payment method: net banking, debit card, RTGS/NEFT, or payment at an authorised bank branch.
Step 8: Complete the payment. Save the Challan Identification Number (CIN) shown on the confirmation screen. You will need this while filling your ITR.
Important: After paying, wait at least 4 to 5 hours before filing your ITR. The payment takes time to reflect in your pre-filled ITR data on the portal. Filing immediately after payment can result in the challan not appearing, and your return may get processed with an outstanding demand even though you have paid.
Where to Enter Self Assessment Tax in Your ITR
When you file your ITR through the online filing process, the portal asks you to confirm your tax payments. Here is where the challan details go:
In ITR-1 and ITR-2, navigate to the Tax Details tab and scroll to Details of Advance Tax and Self Assessment Tax Payments. Enter the BSR code, challan serial number, date of deposit, and amount exactly as shown on your challan receipt.
The portal will then compute whether a refund is due or if any balance tax remains. If the challan has reflected correctly, your tax payable should show as zero.
Key Points for FY 2025-26 Filing
- Self assessment tax for FY 2025-26 falls under the Income Tax Act 1961. Use Tab 1 on the portal, not Tab 2 (which applies to Tax Year 2026-27 under the new Income Tax Act 2025)
- Challan type is always (300) Self Assessment Tax in ITNS 280
- Assessment Year to select: AY 2026-27
- Pay before July 31, 2026 to avoid Section 234A interest. You can make the payment directly on the Income Tax e-filing portal
- Keep the challan receipt safe for your records, at least until the assessment for that year is complete
- If you are filing a belated or revised return, any additional tax liability arising from corrections must also be paid as self assessment tax before submitting
Common Mistakes to Avoid
Selecting the wrong challan type: Accidentally selecting Advance Tax (100) instead of Self Assessment Tax (300) creates a mismatch in your ITR and can trigger a demand notice. Always verify the challan type before proceeding to payment.
Filing ITR immediately after payment: The challan takes a few hours to appear in your portal data. Filing before it updates means your return will show outstanding tax demand even though you have paid. Wait 4 to 5 hours after payment.
Not including Section 234B interest: If 234B interest applies to you, include it in the self assessment tax payment itself. Filing without covering the interest will result in a demand notice after return processing.
Wrong assessment year: For FY 2025-26 income, the assessment year is AY 2026-27. Paying under the wrong AY means the credit will not get matched to your return.
Frequently Asked Questions
Q: What if I overpay self assessment tax? The excess amount is treated as a refund. The Income Tax Department credits it to your registered bank account after processing your ITR. You can track the refund status using the ITR refund status check guide.
Q: Can I pay self assessment tax in cash? Yes, you can walk into an authorised bank branch and pay using the physical ITNS 280 challan. However, online payment is faster and the challan reflects in your profile within a few hours.
Q: Is self assessment tax applicable under both old and new tax regimes? Yes. The concept applies regardless of which regime you choose. The tax liability amount will differ based on your regime, but the payment process is identical under both.
Q: What is the difference between self assessment tax and tax on regular assessment? Tax on regular assessment (challan type 400) is paid when the Income Tax Department raises a demand after scrutiny or processing your return. Self assessment tax (challan type 300) is what you calculate and pay voluntarily before filing your ITR.
Q: I am filing my return under the new Income Tax Act 2025. Do I still follow the same process? For FY 2025-26 returns filed in July 2026, the Act 1961 rules apply (Tab 1 on the portal). The self assessment tax payment process remains exactly the same. Tab 2 and the new Act 2025 provisions apply from Tax Year 2026-27 onwards, which means the July 2027 filing cycle.
Conclusion
Self assessment tax is not something to calculate at the last minute. If there is any balance tax after accounting for TDS and advance tax, calculate it accurately, add applicable interest under Section 234B, pay it using challan type 300 before July 31, 2026, and then file your ITR. Getting this right the first time saves you from demand notices, rectification requests, and unnecessary follow-ups with the department.
