Uniform Commercial Code (UCC) - Article 4A: Federal legislation governing funds transfers and payment mechanisms between parties. Essential for structuring payment terms and electronic fund transfers.

E-SIGN Act: Federal law ensuring the legal validity of electronic signatures and records in commercial transactions, crucial for modern payment contracts.

Truth in Lending Act (TILA): Federal regulation requiring disclosure of key terms and costs in consumer credit transactions, applicable if the payment contract involves consumer credit.

Fair Debt Collection Practices Act (FDCPA): Federal law regulating debt collection practices, relevant for enforcement provisions in payment contracts.

Bank Secrecy Act (BSA): Federal law requiring financial institutions to assist government agencies in detecting and preventing money laundering, particularly relevant for large payment transactions.

State Contract Laws: Varying by state, these laws govern contract formation, enforcement, and remedies specific to the jurisdiction.

State Usury Laws: State-specific regulations limiting interest rates and fees that can be charged in payment arrangements.

State Electronic Transaction Laws: State-level regulations governing electronic transactions and digital signatures, complementing federal E-SIGN Act.

State Consumer Protection Laws: State-specific regulations protecting consumers in financial transactions, varying by jurisdiction.

Federal Reserve Regulations: Banking regulations affecting payment processing, fund transfers, and financial institution responsibilities.

CFPB Regulations: Consumer Financial Protection Bureau rules governing consumer financial products and services, including payment arrangements.

Anti-Money Laundering Regulations: Federal requirements for preventing and detecting money laundering in financial transactions.

IRS Requirements: Federal tax regulations affecting payment reporting, withholding, and documentation requirements.