Filing your ITR after the due date can lead to monetary costs and loss of tax benefits. The Income-tax Act prescribes both late fees/penalties and interest charges depending on your situation. Here’s a detailed breakdown:

🔹 1. Late Filing Fee – Section 234F

• If you file your ITR after the due date (31st July for most individuals):
  • Income up to ₹5 lakh → Maximum late fee ₹1,000.
  • Income above ₹5 lakh →
    • Filed after due date but on/before 31st Dec → ₹5,000.
    • Filed between 1st Jan and 31st Mar → ₹10,000.

🔹 2. Interest on Tax Payable

1. Section 234A – Delay in Filing ITR
   • Rate: 1% per month (or part of a month).
   • Period: From due date of filing return till actual filing date.
   • On: Unpaid tax liability.
   • Example: If return due on 31st July but filed on 20th September, interest applies for 2 months (Aug & Sep).
2. Section 234B – Default in Advance Tax
   • Applies if you did not pay advance tax, or paid less than 90% of your liability.
   • Rate: 1% per month (or part of a month).
   • Period: From 1st April of next financial year till date of payment.
   • On: Assessed tax minus advance tax & TDS.
3. Section 234C – Deferment of Advance Tax
   • Applies if advance tax is not paid in correct installments.
   • Due dates for advance tax (Individuals):
     • 15th June – 15%
     • 15th Sept – 45%
     • 15th Dec – 75%
     • 15th Mar – 100%
   • Rate: 1% per month (or part thereof).
   • Period: Fixed – 3 months (for June, Sept, Dec) or 1 month (for March).
   • On: Shortfall in installment.

🔹 3. Loss of Benefits

• You cannot carry forward capital losses or business losses if you miss the due date.
• Loss from house property can still be carried forward.

🔹 4. Refund Delay

• If you are eligible for a refund, you will get it only after filing.
• Late filing = refund delayed.

🔹 5. Increased Risk of Scrutiny

• Late filing often increases chances of your return being picked for scrutiny/notice.

🔹 6. Extreme Cases

• If you don’t file at all despite taxable income, the department may treat it as tax evasion, which can attract prosecution or penalties under other sections.

It’s always best to file your ITR within the due date to avoid late fees, interest charges, and loss of tax benefits. Filing on time also ensures quicker refunds and a clean tax record.