The U.S. Department of Labor finalized a rule requiring pharmacy benefit managers (PBMs) to disclose extensive compensation and payment data to self-insured employer plan clients. Regulators estimate the change could reduce drug costs for employers and workers by $22 billion over a decade. The disclosure mandate will cover rebate arrangements with drug manufacturers and “spread” payments where PBMs reimburse pharmacies at different rates than what plans pay. Under the final rule, which takes effect July 2027, PBMs must share information when negotiating or renewing employer contracts and at least every six months afterward. Employers will be able to audit disclosures once per year. The rule also includes penalties and possible contract invalidation for noncompliance, setting up a high-stakes compliance test for PBM operating models built around opaque fee structures.