This discussion clarifies whether a Unique Document Identification Number (UDIN) can be legally issued for a tax audit performed by a Chartered Accountant (CA) other than the one who conducted the audit. The consensus is that a UDIN is not permissible for such a scenario when filing with the income tax department. While a 'true copy' certification might not require a UDIN, its use for tax audit purposes by a different CA is legally restricted.