Business Activity Tax Simplification Act of 2026

The Business Activity Tax Simplification Act of 2026 updates federal rules to clarify when states can tax businesses operating across state lines, primarily affecting interstate companies and digital service providers. It expands the definition of taxable activities to include digital goods and services while clarifying that independent contractors do not create tax liability for their principal companies. The bill also establishes a minimum physical presence requirement, stating that states generally cannot tax businesses unless they have employees, agents, or property in the state for at least 15 days. Additionally, the law extends existing federal protections against state taxation to various "other business activity taxes" and provides specific guidelines for how states should calculate taxes on groups of affiliated companies. These changes are designed to take effect for taxable periods starting on or after January 1, 2026.