When the existence of a debt is admitted by the debtor or established by the evidence of the creditor, the burden of proving extinguishment by payment dissolves upon the debtor who claims payment
In subrogation, the person who pays for the debtor is put into the shoes of the creditor
In reimbursement, the third person has merely the bare right to be refunded to the extent provided without the right to the guarantees and securities of the original obligation
If a stranger to the obligation willingly paid the debt of a debtor without the intention to be reimbursed or to recover the amount from the debtor, then it may be considered as a donation with the consent of the debtor
There must be performance of the prestation in lieu of payment
There must be some different between the prestation due and that which is given in substitution
There must be an agreement between the creditor and debtor that the obligation is immediately extinguished by reason if the performance of a prestation differs from that due
If the obligation consists in the delivery of a specific thing, the very thing due must be delivered
If the obligation is to deliver a generic thing, the purpose of the obligation and other circumstances shall be taken into consideration to determine the quality or kind of thing to be delivered
The payment of debts in money shall be made in the currency stipulated, and if it is not possible to deliver such currency, then in the currency which is the legal tender in the Philippines
The delivery of promissory notes payable to order or bills of exchange or other mercantile documents shall produce the effect of payment only when they have been cashed, or when through the fault of the creditor they have been impaired
RA No. 529 required the payment of domestic obligations in Philippine currency and declared as null and void any provision requiring payment in a foreign currency
RA No. 8183 repealed RA No. 529, so there is no longer any impediment to having obligations or transactions paid in a foreign currency as long as the parties agree
Promissory notes, checks, bills of exchange and other commercial documents are not legal tender and, therefore, the creditor cannot be compelled to accept them