I've been playing with the Tax forms recently. and found that when changing country, There's a box below containing tax treaty info also changing. That means, envato is calculating % based on the country. There's no tool available for envato to check whether a Tax ID is valid or not.
So, It's not a problem if you put your identity card or your mobile number (Ofcouse you can enter PAN card also) Envato will deduct only 15% if India is chosen.
Shhhhh... don't tell envato about this