Internal Revenue Code (IRC): Federal tax code that provides the foundation for tax regulations and compliance requirements in the United States

AICPA Professional Standards: Guidelines set by the American Institute of CPAs that establish professional requirements for conducting tax services and audits

Treasury Department Circular 230: Federal regulations governing practice before the IRS, including ethical requirements and professional responsibilities

State Sales Tax Laws: Individual state regulations governing sales and use tax, including specific rates, exemptions, and filing requirements

Economic Nexus Requirements: State-specific thresholds that determine when businesses must collect and remit sales tax based on economic activity

Generally Accepted Auditing Standards (GAAS): Professional standards for conducting audits, including planning, execution, and reporting requirements

Statements on Standards for Tax Services (SSTS): Professional standards specific to tax practice that provide guidance on tax services and related responsibilities

IRC Section 7216: Federal regulation governing the disclosure and use of tax return information by tax preparers

Gramm-Leach-Bliley Act: Federal law requiring financial institutions to explain their information-sharing practices and protect sensitive data

State Statutes of Limitations: Time limits set by each state for assessment, collection, and refund of sales taxes

Record Retention Requirements: State and federal requirements for maintaining tax-related documentation and supporting materials

Uniform Commercial Code (UCC): Standardized set of business laws regulating commercial transactions across all states

State Consumer Protection Laws: Regulations protecting consumers from unfair practices, including requirements for professional service agreements

State Board of Accountancy Regulations: State-specific rules governing the practice of public accounting and professional services