The Bureau of Labor Statistics publishes April 2026 CPI data on May 12 at 8:30 a.m. ET. This report is the first to capture cost pass-through from the April 2 tariff implementation. Economists forecast headline CPI at 3.7% to 3.8% year over year, up from 3.3% in March, with a monthly increase near 0.6%. For self-insured employers, the numbers that matter sit in four sub-indices: medical care services, hospital services, motor vehicle insurance, and auto body repair.
The tariff backdrop makes this release different from a routine monthly print. Section 301 duties on Chinese-sourced medical devices and supplies now layer on top of existing tariffs, pushing effective rates above 40% for some product categories. A November 2025 study from the UNC Center for the Business of Health found that 62% of medical devices used in the U.S. are imported, with 80% to 90% of PPE and medical supplies sourced abroad. Johnson & Johnson’s MedTech division has projected $400 million in additional tariff-related costs; Siemens estimates $235 million to $350 million. Those input costs flow through to hospital charges, and from hospital charges into the medical severity component of workers’ comp, health plan, and hospital professional liability reserves.
Who it affects
Self-insured employers and captives with medical severity exposure across any of three lines. Workers’ compensation programs absorb hospital and medical equipment cost increases directly through open medical-only and lost-time claims. Commercial auto programs face tariff-driven inflation in sensors, cameras, EV battery components, and body panels that feed repair cost severity. Hospital professional liability captives feel the secondary effect: when hospitals’ input costs rise, the economic damages component of malpractice claims (lost revenue, inflated life-care plans) rises with them.
The reserve mechanism
The mechanism is severity trend across multiple coverage lines, and the risk is that current trend picks were calibrated to pre-tariff data. In March, the hospital services sub-index ran at 6.4% year over year while the broader medical care index sat at 3.1%. That gap already posed a question about whether blended medical trend factors were adequate for hospital-heavy claim mixes. If April’s hospital services reading accelerates further on tariff pass-through, severity trend assumptions set during year-end 2025 reserve studies will be stale by mid-year.
The compounding problem is that tariff costs do not wash out. Unlike a weather event or a one-time legal ruling, tariff-driven input cost increases embed permanently into the supply chain. Every subsequent development period carries the higher cost base forward, meaning the severity gap compounds rather than self-corrects. NCCI flagged this dynamic in its April 2026 Medical Inflation Insights report, noting that medical equipment and supply prices had already accelerated in early 2026 and forecasting that the moderation in overall WC medical price growth was “unlikely to be sustained.”
What this means for your next review
Tomorrow’s print will either confirm or moderate the severity concern. Three sub-indices to watch at 8:30 a.m.:
- Medical care services (March: 3.7% YoY). A reading above 4% signals tariff costs are reaching the provider level.
- Hospital services (March: 6.4% YoY, +0.4% MoM). A monthly print above 0.5% suggests the February-to-March deceleration was temporary.
- Motor vehicle insurance and auto body repair. These categories have been running in mid-single digits; a tariff-driven acceleration strengthens the case for revising commercial auto severity selections.
If any of these readings surprise to the upside, ask your actuary whether the medical or auto severity trend factor in your current reserve study still reflects the data, and whether pre-tariff and post-tariff accident periods should be separated at the next review.