On June 11, 2026, PwC’s Health Research Institute set the 2027 group medical cost trend at 9%, with 8.5% for the individual market, the highest projection in 17 years (PwC, Behind the Numbers 2027). The figure is built from interviews with actuaries at 27 health plans covering more than 103 million employer members (Fierce Healthcare). PwC also revised its 2026 group projection upward, from 8.5% to 9% (Becker’s). The drivers are familiar and stacking: GLP-1 utilization, specialty and cell-and-gene therapy, behavioral health, hospital pricing, and, newly, AI-assisted revenue optimization by providers, which 70% of plans now rank as a top-three cost driver.
Who it affects
Self-funded employers of every size, but especially the 200- to 2,000-employee plans that carry direct claims risk with specific stop-loss deductibles in the $200,000 to $350,000 range and rarely staff their own actuaries. It also hits group medical stop-loss captives, the fronting carriers behind them, and any benefits CFO who signs a year-end health-plan accrual off a trend assumption chosen last spring.
The reserve mechanism
Health-plan IBNR is a completion-factor and PMPM (per member per month) projection, and the selected trend scales both the incurred estimate and the tail. Understate trend by even a point or two and you understate the incurred estimate that feeds the reserve. A plan still running a 6% or 7% trend against a 9% benchmark carries a direct IBNR shortfall on the balance sheet today; the gap is not a 2027 budget problem, it is an under-accrual of the 2026 year-end liability that will surface in fourth-quarter runout. Trend is the single largest lever in the roll-forward, and for the incomplete recent months it quietly drives roughly half the reserve.
The same trend erodes stop-loss protection through leverage. A fixed-dollar specific deductible does not move with medical inflation, so 9% trend pushes more of every large claim above the attachment each year. That is the mechanism behind Segal’s finding that specific stop-loss premiums rose 12.7% for plans that held deductibles flat, well above gross medical trend (our coverage). GLP-1 volume is the accelerant underneath it, with prescriptions reaching roughly 3.5 million in December 2025, nearly double a year earlier.
Where this shows up in your reserves
Look at the trend factor line in your actuary’s IBNR memo and the PMPM projection for the three or four most recent, least-complete months, where the completion factor does the most work. Reconcile the selected trend against your own emerging claim experience, not just the PwC aggregate: if GLP-1 and specialty scripts are running hotter in your data, the industry number is a floor. Then check the stop-loss reconciliation, where a flat deductible plus 9% trend shows up as a rising reimbursed layer.
What this means for your next review
Put the trend assumption on the agenda now. Q3 is when self-funded plans lock 2027 trend, budgets, and stop-loss attachment points, and a plan that sets trend a point low will look fine until the runout catches up. See what’s driving your IBNR higher and our plain-English guide to self-funded IBNR for the mechanics.
Decision-maker checklist
- Ask your actuary what trend is baked into the current IBNR and the 2026 year-end accrual, and how it compares to PwC’s 9%.
- Quantify the sensitivity: how much does a 1-point trend miss move IBNR and expected stop-loss reimbursements?
- Pull GLP-1 and specialty-drug claims from your own data and test whether they are trending faster than the trend you selected.
- Before you reset the 2027 specific deductible, model the leverage: a flat attachment plus 9% trend raises your effective retention every year.