The department already knows most of your income: it is in your AIS and Form 26AS. A good return starts from those, matches your own papers against them, and explains any difference before the department asks.
Return
Due date (return filed in 2026)
Salaried and other individuals without business income
31 July
Business or professional income, no tax audit
31 August (moved from 31 July by the Finance Act 2026)
Where a tax audit applies, and companies
31 October
Everyone
PAN, and Aadhaar linked to it
Form 26AS, the Annual Information Statement (AIS) and TIS — downloaded from the e-filing portal
Bank account details, including the account for any refund
Interest certificates from banks and post office deposits, and dividend details
Capital gains statements from your broker and mutual funds, and papers for any property sold
Last year's return
Salaried
Form 16 from every employer you worked for during the year
If you claim the old regime: proofs for section 123 (old 80C), section 126 (old 80D) and other deductions
Home loan interest certificate, for section 22 (old 24(b))
Rent receipts and the landlord's PAN where rent is above ₹1 lakh a year, for HRA under the old regime
Business or profession
Books of account, profit and loss statement and balance sheet
GSTR-1 and GSTR-3B for the year, to reconcile turnover
TDS certificates from customers (Form 16A)
Loan statements and purchase invoices for assets
Tax audit report, where a tax audit applies
What most often goes wrong
Not e-verifying within 30 days of filing. Until it is verified, the return is not complete — and a late verification counts as the filing date.
Income or TDS that does not match the AIS or Form 26AS. This is the most common source of a notice.
The wrong ITR form. That makes the return defective under section 139(9), and a defective return not corrected in time is treated as never filed.
Reviewed by Ravi Kiran Garlapati, Managing Director, Vedanthh Business & Investment Advisory Pvt. Ltd..
Checked November 2026. Rules change with each Budget and notification — for your own case, ask us.