CMS made impactful changes to the Federal physician self-referral law’s (i.e., Stark Law’s) regulations in its Final Rule that were effective January 19, 2021 (with the exception of the changes to 42 C.F.R. § 411.352(i) that are effective January 1, 2022). Although lengthy (190 pages/3-column format), the Final Rule is worth the read with multiple clarifications and revisions to the dense regulations.