UDIN stands for Unique Document Identification Number — an 18-digit code that every Chartered Accountant must generate on the ICAI portal within 60 days of signing or certifying any document. Mandatory since January 2019, it enables banks, regulators, and clients to verify any CA-certified document online and prevents forgery.
UDIN Full Form and What the 18 Digits Mean
The UDIN is structured as: YYYYMMMMNNNNNNNN where:
- YYYY — Year of generation
- MMMM — Membership number of the CA (6 digits, zero-padded)
- NNNNNNNN — 8 random alphanumeric characters
Example: 26012345ABCDEF12 — generated in 2026 by MRN 012345.
Which Documents Require UDIN?
UDIN is mandatory for all documents signed, certified, or attested by a CA in their professional capacity, including:
- Tax audit reports (Form 3CA, 3CB, 3CD)
- GST audit reports (Form 9C)
- Statutory audit reports under Companies Act
- Certificates (net worth, turnover for bank loans, export performance)
- Form 15CB (foreign remittance certificates)
- Transfer pricing certificates (Form 3CEB)
- Financial statements certified by a CA
Not required for: Internal audit reports, management letters, representations, advisory opinions.
How to Generate UDIN on the ICAI Portal
- Go to udin.icai.org
- Log in with your ICAI membership number and OTP
- Click Generate UDIN
- Select the document type from the dropdown
- Enter the document date and financial year
- Enter key financial figures from the document (turnover, net profit, etc.) — these are used for verification
- Click Generate — your 18-digit UDIN is created instantly
- Stamp or write the UDIN on the physical/digital document before delivering it
Time limit: UDIN must be generated within 15 days of the document date (60 days was the earlier limit; ICAI tightened this). Update it before this deadline.
Penalty for Not Generating UDIN
Failing to generate UDIN is professional misconduct under the Chartered Accountants Act. ICAI can initiate disciplinary proceedings. Additionally, banks and regulators now routinely verify UDIN online — a document without a valid UDIN may be rejected for loan applications, tender submissions, or regulatory filings.
How CA Firms Should Track UDIN
Most CA firms generate UDINs but struggle to track them — especially when multiple partners sign different documents across different clients. Best practice:
- Maintain a UDIN register (date, client, document type, UDIN) — can be Excel or software
- Attach the UDIN to the document file in your document management system
- Set a calendar reminder 10 days before the 15-day deadline for each pending UDIN
- During ICAI peer review, the reviewer will ask for the UDIN register — have it ready
Track every UDIN across all clients automatically. TaxZeo logs UDINs against documents and alerts you before deadlines — no more missed UDIN submissions or peer review surprises.
Explore TaxZeo →Frequently Asked Questions
Can I revise or cancel a UDIN after generating it?
Yes. You can revise a UDIN on the ICAI portal within 60 days. After that, you can only deactivate it by marking it as "Withdrawn" with a reason. Once deactivated, the document becomes invalid and a fresh UDIN must be generated.
What happens if I generate UDIN after the document date?
ICAI allows backdating UDIN up to 15 days before the current date. If you miss the window, generate it immediately and note the delay in your firm's UDIN register — late generation is better than no generation.
Is UDIN required for certified copies?
No. UDIN is required only for original certifications and reports signed by a CA. Certified true copies of documents already bearing a UDIN do not need a separate UDIN.