After introducing unique account numbers for tax-payers (PAN) and those for tax deductors (TAN), the government will this fiscal introduce a unique document identification number (DIN) to be quoted on every income-tax related communication.

The department will soon put in place a tech-based mechanism to generate DIN which will be allotted to not only tax-payers but also the officials of the department from October this year, which will become essential while filing the annual income-tax return of the financial year (2010-11 ).

According to a Central Board of Direct Taxes, insertion of new Section 282B in the I-T Act, DIN will be mandatory in respect of every notice, order, letter or any correspondence with the department.

The number will be generated by the department and will be useful essentially for error-free filing of tax returns , claiming refunds and other communication with the department by the assesses, a senior finance ministry official said. Tax-payers and tax deductors currently are required to quote PAN and TAN among others for filing returns with the department.

Assesses will not be put to any trouble as the numbers will be generated and allotted by the department itself. Once allotted , the assessee will have to quote it thereon. I-T officials will also be allotted the numbers as the effort is to streamline the process, the official said.

According to section 282B of the Income Tax Act, which deals with DIN, in respect of every notice, order, letter or any correspondence issued by him (I-T authority) to any other income tax authority or assessee or any other person and such number shall be quoted thereon.

It is further provided that where the notice, order, letter or any correspondence issued by any income-tax authority does not bear a Document Identification Number, such notice, order, letter or any correspondence shall be treated as invalid and shall be deemed never to have been issued.