Physical Receipt

• A physical receipt is not considered conclusive evidence, but it is the strongest evidence. In California, if a person possesses the "order... for the payment of money" he is assumed to have paid for the item in question, according to LoisLaw.
  
  

Presumed Obligation

• In California, any money paid from one person to another is presumed to have been due to the payee, according to California Evidence Code Section 631.
  
  

Payment of Judgment

• The courts in California presume a debtor has made full or partial payment when two requirements have been met, according to California Code of Civil Procedure Section 116.850. The debtor of a judgment must file with the clerk a canceled check or money order and a declaration stating the debtor has made a payment.