Contracts Act (Cap. 53): Primary legislation governing contract formation, validity, and enforcement in Singapore. Essential for establishing the basic legal framework of the promissory note as a contract.

Bills of Exchange Act (Cap. 23): Governs negotiable instruments including promissory notes, defining their essential characteristics, rights, and obligations of parties involved.

Moneylenders Act (Cap. 188): Relevant if the promissory note involves money lending activities. Sets restrictions on interest rates and regulates money lending practices.

Civil Law Act (Cap. 43): Contains provisions affecting contractual relationships and civil obligations in Singapore.

Limitation Act (Cap. 163): Sets the time limit (generally 6 years) within which legal action can be taken to enforce the promissory note.

Companies Act: Relevant if the promissory note is used as a security instrument, particularly for corporate transactions.

Stamp Duties Act (Cap. 312): Governs the stamp duties payable on certain instruments, including promissory notes in specific circumstances.

Formation Requirements: Legal requirements including clear payment terms, definite sum, written form, and maker's signature.

Interest Rate Regulations: Rules governing permissible interest rates and usury laws applicable to promissory notes in Singapore.