S. 4639 · 119th Congress IRS Whistleblower Program Improvement Act StageIn committee SponsorChuck Grassley Introduced2026-05-21 Latest action2026-05-21 · Introduced in Senate Follow Summary Text Subjects Cosponsors (3) Votes (0) Actions Cosponsors (3) Susan Collins Current member Senate ME Republican Maggie Hassan Current member Senate NH Democrat Ron Wyden Current member Senate OR Democrat