UDIN — What the Unique Document Identification Number Is, Which CA Certificates and Reports Must Carry It, How a Bank or Buyer Verifies It at udin.icai.org, the 60-Day Generation Rule, Revocation, and the Income-Tax Portal Linkage for Audit Reports

The Unique Document Identification Number is an 18-digit code that a practising Chartered Accountant generates on ICAI's portal for every document he or she signs in an attest capacity. It is built from the year (two digits), the member's registration number (six digits) and a random ten-character code, so 26123456ABCDEFGHIJ identifies one document signed by one member in 2026. The number is written on the document below the signature. Because the CA records the client's name, the type of document and the key figures while generating it, anyone holding the certificate can confirm on the portal that a real, practising CA issued that document, on that date, with those figures — and cannot be shown a certificate the CA never signed.

1. 1Open udin.icai.org and choose 'Verify UDIN' (no login needed). Enter the 18-digit number exactly as printed, your name and mobile/e-mail, and the captcha.
2. 2The portal returns the member's name and registration number, the firm name, the date of generation, the document type and the description/figures the CA recorded (for example 'Net worth certificate — ₹1.25 crore as on 31 March 2026 — for ABC Traders').
3. 3Match three things: the member's name and number against the signature block and the ICAI 'Know your member' search; the document description against what you are holding; the figures against the certificate. A mismatch in any of them is a reason to call the CA directly on a number from the ICAI record, not from the certificate.
4. 4Status 'Revoked' means the CA withdrew the UDIN (a wrong figure, a superseded certificate); the document should not be relied on. 'Not found' means no such number exists — treat the certificate as unverified.
5. 5Audit reports: the income-tax e-filing portal validates the UDIN quoted on Form 3CD and other audit forms against ICAI's data; the report is treated as invalid if a valid UDIN is not updated within the time allowed (60 days), and the return is defective in consequence.

• •Only full-time practising members (Fellow or Associate holding a certificate of practice) can register on the UDIN portal with their membership number, date of birth and enrolment date; partners generate under their own numbers.
• •Generate within 60 days of signing (extended from the original 15 days); bulk generation and API-based generation from audit software are available; a UDIN generated after 60 days is flagged and, for audit reports, may not be accepted by the income-tax portal.
• •One UDIN per document; a certificate issued in copies carries the same number; a revised certificate needs a new UDIN and revocation of the old one, with reasons recorded.
• •The portal captures financial figures or 'key values' (two to five) chosen by the member — these are what a verifier sees; choose figures that identify the document unambiguously.
• •Non-generation is professional misconduct under the Chartered Accountants Act (Schedule II); ICAI's Disciplinary Directorate acts on complaints from banks and regulators.
• •Multipurpose use: RBI, SEBI, banks, MCA (for certain forms), DGFT and the income-tax department consume UDIN data; the Institute's 'UDIN Directorate' publishes FAQs updated periodically.