Visitor Visa for Parents self employees

[immihelp]

Hello

I want to invite my mother and inlaws to USA on visitor visa. I am self employeed green card holder working as consultant.I was on W2 till December2006.

What procedure I should follow. What all supporting documents I will need?

Thanks

[immihelp]

You need to show tax returns and other proof of income such as contracts, invoices, payments from customers etc.