Department can seek information for any period which you are obliged to supply. But SCN can be issued upto a time of 1 year in case of central excise and 18 months in case of service tax related issues provided department is informed on the subject. If any issue came to the light of department and department allege that information was not disclosed to department but they came to know only after initiation of any action in such case they can invoke extended period of limitation.
In case you have already disclosed every thing in the year 2001, and you have dated acknowledgement from the department, department cannot issue show cause notice after a lapse of 10 years. In case they decide to do so it will not stand before the higher appellate level.
Regards,
V.Venkat Raman