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. According to official sources, 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. The Aykar Sampark Kendras will hand out the DIN for this purpose.