Taxpayers will now have to procure a 'new number' for filing returns and making any communication with the Income Tax department.

The unique Document identification number (DIN), on the lines of numbers like PAN and TAN, will be quoted on "every" income tax-related communication, including returns to be filed next year for the financial year 2010-11.

According to the new guidelines brought out by the Central Board of Direct Taxes (CBDT), the DIN will be mandatory "in respect of every notice, order, letter or any correspondence" with the department, by the taxpayers.

"The DIN will be generated by the I-T 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.

The 'Aykar Sampark Kendras' will hand out the DIN from this month, the official said.

Assesses will not be put to any trouble, as the numbers will be generated and allotted by the department itself.

I-T officials will also be allotted the numbers in order to streamline the process, the official said, adding, the number has to be produced thereon for every activity with the department.

Taxpayers and tax collectors are currently required to quote Permanent Account Number (PAN) and Tax Deduction and Collection Account Number (TAN) among others when returns are filed with the department.

According to section 282B of the Income Tax Act that deals with DIN, if the document sent to the tax authority does not bear this unique computer-generated number then "such document, letter or any correspondence shall be treated as invalid and shall be deemed never to have been received."

DIN is aimed at bringing more transparency in tax administration as the whole exercise involves a number of documents and proformas. Apart from regular filing of taxes, a taxpayer deals with the department for various other financial services, which DIN will help to ease, the official said.