If you are just applying for a simple TRV, not a supervisa, then I don't see why you have to provide your income tax assessment. A current bank statement with decent funds should suffice. Check to see if there are specific instructions for individual countries. In your letter of invitation, state how and when you met the guest and why you are inviting them to visit.
Thanks Pippin. No idea where to check if there are specific instructions for individual countries. I wish someone who actually has experience with friends/family visiting from India could advise me. The guy at the Canadian visa office at my friend's city is demanding that I should provide ALL of them (proof of employment AND T4 AND notice of assessment AND bank statement). I don't even feel safe sending all that to a far off place where unwanted eyes may fall on them.