(a) Except as provided by Sections 1157.005 and 1157.102, a claim for money against an estate must be supported by an affidavit that states:
(1) that the claim is just;
(2) that all legal offsets, payments, and credits known to the affiant have been allowed; and
(3) if the claim is not founded on a written instrument or account, the facts on which the claim is founded.
(b) A photostatic copy of an exhibit or voucher necessary to prove a claim under this section may be offered with and attached to the claim instead of attaching the original.