It's just like an application you write to your AO stating the reason for delayed for not filling the return with rough calculation of income with deduction and net taxable income
As per that period slab rate is it taxable or not taxable like incometax calculation after crossing verification by you
Then the AO will verify the situation as per your letter request if he satisfy with it then he makes you to fill the forms of return in front of him with a acceptance permission letter
Then one set of those returns copy n letter you keep with you and second copy you have to send to Bangalore office
Then you claim those tds refund in your current year while filling return