CFR›Title 26›Chapter I›Part 509 ContainsSubpart ECFRd60dfb9daabf2aeCorpusDaily eCFRDisplayed edition2026-04-24Last updated2026-04-24 PART 509—SWITZERLAND Subparts ECFRd60dfb9daabf2ae Subpart—General Income Tax Sections 509.101–509.121 Authority26 U.S.C. 62, 3791 and 7805. Previous 420 Part 420—Temporary Regulations on Procedure and Administration Under the Employee Retirement Income Security Act of 1974 Next 513 Part 513—Ireland