Personal Data Protection Act (PDPA): Singapore's primary data protection legislation that governs the collection, use, and disclosure of personal data. Relevant when the letter contains personal information, requiring compliance with data protection obligations and consent requirements.

Employment Act: Singapore's main employment law that may be relevant if the letter is in an employment context, particularly for recognition of service or contributions, and any mentions of employment terms.

Contract Law (Singapore Common Law): Fundamental principles of contract law based on Singapore's Common Law system, covering basic elements of valid contracts, enforceability of promises, and clear expression of intent.

Electronic Transactions Act: Legislation governing electronic transactions and digital signatures in Singapore, relevant if the letter is to be executed electronically, including provisions for legal validity of electronic signatures and digital documentation requirements.

Evidence Act: Singapore law governing the admissibility of evidence, including requirements for document authentication and establishing evidentiary value of written communications.