It also said that those tax payers who have already posted the corresponding ITR-V to its centre and have not received an acknowledgement for the same for these periods, should post it again.
The department said it would not be able to process refunds and validate their I-T returns if the same is not done in such cases.
The deadline for this task has been set at October 31, 2013.
According to rules, a taxpayer who has filed an e-return without digital signature, has to mandatorily post the corresponding ITR-V printout to the department's CPC in Bangalore by post, failing which the returns are considered invalid.
Taxpayers, according to the latest I-T advisory, should send their ITR-V only by "ordinary post" or by "speed post". The current advisory is for those taxpayers who have filed their returns for Assessment Year (AY) 2011-12 and 2012-13.
"There are many taxpayers who have uploaded their Income Tax Returns electronically (without digital signature certificate) for AY 2011-12 (filed during FY 2012-13) and ITRs of AY 2012-13 (filed on or after April 1, 2012), but have either not filed the corresponding ITR-V or have filed it with the local I-T office.
"ITR-V is accepted only at the Centralised Processing Centre (CPC) of the I-T department at Bengaluru by ordinary post or speed post. Therefore, a final opportunity is being given to such taxpayers to regularise their I-T returns," the department's advisory said.