UDIN stands for Unique Document Identification Number. It is a 18-digit system-generated unique number for every document certified/attested by Full time Practicing Chartered Accountants (CAs) in India. The UDIN is generated by the ICAI (Institute of Chartered Accountants of India) and is registered on the UDIN portal.

UDIN stands for Unique Document Identification Number. It is a 18-digit system-generated unique number for every document certified/attested by Full time Practicing Chartered Accountants (CAs) in India. The UDIN is generated by the ICAI (Institute of Chartered Accountants of India) and is registered on the UDIN portal.

The UDIN was introduced in 2019 to curb the malpractices of certification by non-CAs by impersonating themselves as CAs. It also helps to secure the certificates/reports/documents attested/certified by practicing CAs. This will also enable the Regulators/Banks/Third parties to check the authenticity of the certificates/reports/documents.

The UDIN is mandatory for the following documents:

* All certificates

* GST and Income Tax Audit

* All Audit and Assurance Functions

* Balance Sheet (in case the financial statements are subject to statutory audit)

The UDIN is a secure and reliable way to identify documents certified/attested by CAs. It helps to protect stakeholders from fraudulent documents and ensures the authenticity of the documents.

Here is the format of the UDIN:

```

YY-MMMMM-ZZ-NANANANAN

```

* YY: Last two digits of the current year

* MMMMM: Membership number of the CA

* ZZ: Code for Ministry

* NANANANAN: Alpha-numeric random number generated by the system

For example, the UDIN for a document certified/attested by a CA with membership number 1234567890 in the Ministry of Corporate Affairs in the year 2023 would be:

```

23-1234567890-01-ABCDEFGH

```

The UDIN can be found on the UDIN portal or on the document itself. The UDIN is a valuable tool for stakeholders to verify the authenticity of documents certified/attested by CAs.