Does anyone know what the payment receipt requirements are for a USA client hiring freelancers from other countries? I know I don't need to do a 1099 for them as a foreign freelancer would not need pay US Income taxes. But are there any records I need so I can deduct the payment from my income, beyond a PayPal or credit card receipt that shows I paid them?

I have hired people through sites like eLance and oDesk knowing those sites handle the record keeping for me, but I have someone I'd like to hire directly and I want to make sure the IRS can't come back and deny my deduction of the money I pay him.

Thanks - and I hope this question is appropriate for this forum.