Any money that comes out of an account must have documentation (like a receipt) to prove that the funds were used to pay for an eligible medical expense. This is required by the IRS. This page explore...Any money that comes out of an account must have documentation (like a receipt) to prove that the funds were used to pay for an eligible medical expense. This is required by the IRS. This page explores what information is required in the documentation and how you can easily save it for future reference.