About Digital Signature Certificate :

e-Filing with Pan Encrypted Digital Signature Certificate (DSC) on the Income Tax e-Filing portal has been made mandatory w.e.f first July 2011 for Firms and Individuals whose accounts are need to be audited u/s 44 AB of the Income Tax Act' 1961. For other people who don't go under the above category, e-Filing Income Tax returns might be finished with DSC also. If filing is done electronically utilizing digital signature, there is no required to submit a physical copy of the return. Else a physical printed copy of the filled up Form alongside the copy of the Provisional Acknowledgement Number of your e-Return must be submitted.