Is Form 16 required and of how many recent Saral Form/Form 16 is needs to be retained?

Hi All,

Couple of questions?

1. With Form 16 being filed and on receipt, we will have Saral Form(Form 2d).  Should I retain Form16, when I have Saral Form with me?  If yes, then why?
2. How many years latest Saral Form/Form 16 needs to be retained?

Please add more details.

Thanks
Sunil Kumar