Are past Income tax returns directly linked to one's PAN number. Is there no need to keep the Acknowledgement receipt now with oneself, as in the past to know when tax return was filed with IT department.
I suppose your past years' tax returns have been assessed and you have received either refund or demand orders which you have attended to. If you have not received any assessment order or have not received the refund order where it was due or have not paid a tax demand when it was served on you, please try to get these matters settled by reminding the dept. for refund or pay the demand asked for, if in order.
I would suggest that you retain copies of your tax returns, the original acknowledgements as also refund order copies and demand paid challans for a period of 10 years at least, so that you could answer any queries the dept. may ask you later on. There is a perod beyond which the dept. would not normally ask for information on past assessed/settled returns. Once this period is over, you need not keep these copies.