While not required by law, having the promissory note notarized can provide additional legal protection and evidentiary weight in court should any dispute arise over its enforcement.
A contract, under Philippine law, becomes binding as soon as there is mutual consent between the parties, consideration (payment or exchange of services), and a lawful object (subject matter of the agreement). These elements are enough to form a valid and enforceable contract, even without notarization.
Lending agreements are governed by the Civil Code of the Philippines, along with other relevant laws such as the Lending Company Regulation Act and the Usury Law, although the latter is largely outdated due to the Central Bank's removal of interest rate ceilings.
Ing to Boundy (2012), typically, a written contract will include: Date of agreement. Names of parties to the agreement. Preliminary clauses. Defined terms. Main contract clauses. Schedules/appendices and signature provisions (para. 5).