For years, the pass-through PBM model has been sold as the cure-all for self-funded plans. No more spread pricing. No more hidden revenue streams. Just a transparent admin fee and a fat quarterly check representing 100% of negotiated manufacturer rebates. CFOs frame those checks. Consultants use them as proof their strategy is working. Everyone walks away feeling like the grown-up in the room.
Then the renewal lands, and nobody can figure out why the numbers look so grim.
I've spent two decades inside these arrangements, and I can tell you something most plan sponsors discover too late: that rebate check is quietly poisoning every data system your plan depends on. Your trend reports, your actuarial forecasts, your stop-loss pricing - all of them are operating on gross-cost fiction while the real money sits unrecognized in a completely different universe. And the gap between those two worlds is costing you real dollars, real member trust, and potentially real compliance headaches.
The Split That Breaks Everything
The pipeline works like this. Every time a member fills a prescription, the claim flows from the PBM into your benefits analytics platform. The data says: this drug cost $10,000, the plan paid $8,000, the member paid $2,000. Your dashboards, your trend reports, your PMPM calculations - they all treat that $10,000 as your true exposure.
But under a pass-through contract, your actual cost on that same prescription might be $6,000. The manufacturer rebate, sometimes 40% or more of list price, arrives three months later as an undifferentiated lump sum. Finance books it. The analytics engine never sees it. And every number your team uses to manage the plan remains inflated by thousands of dollars per claim, month after month, year after year.
I once worked with a 10,000-life employer that switched to pass-through, celebrated two years of healthy rebate checks totaling over $2 million, then pushed a 4% employee premium increase based on renewal projections. Those projections were built entirely on gross-cost data. The rebate dollars existed in the general ledger but never touched the actuarial model. The plan sponsor raised costs on workers in response to a phantom crisis. Nobody connected the dots until the trend reports were already baked into next year's budget.
When Stop-Loss Underwriters See Ghosts
The same distortion bleeds into stop-loss pricing. A member on a specialty drug with a $10,000 monthly price tag looks like a walking risk. Underwriters price your renewal off that $120,000 annual run rate. But your net cost might be $60,000. Unless you're submitting rebate-adjusted data - and almost nobody does - you're insuring a liability that doesn't actually exist, paying premiums sized for a ghost.
This is why so many plans stay trapped in copay-only designs. Finance teams look at the gross exposure and panic at the thought of moving to a deductible-based model. They don't realize the net cost picture tells a completely different story.
The Quiet ERISA Problem Nobody Mentions
Then there's the fiduciary angle. ERISA requires plan fiduciaries to act prudently with plan assets, and courts are now being asked how far that duty reaches into drug pricing. A class action against Johnson & Johnson alleging the company failed to keep prescription drug prices reasonable has been dismissed twice for lack of standing and is now on appeal, so the merits remain untested. The arithmetic is straightforward. When a member pays 20% coinsurance on a $10,000 drug and the plan later pockets a $4,000 rebate on that same claim, that member effectively paid 33% of the net cost. If your plan document doesn't define how rebates interact with cost-sharing, and your systems can't true up cost-sharing after rebates land, you hold an exposure you cannot currently measure or defend.
Most benefits administration platforms can't perform that rebate-to-claim matching today. They were never designed to. So the burden falls on the plan sponsor to bridge the gap manually - something almost nobody has the bandwidth or data architecture to do.
The Rules Are Catching Up
The rebate check is about to get harder to keep in a drawer. The Consolidated Appropriations Act, 2026, signed February 3, requires PBMs to pass through 100 percent of rebates, fees, and other manufacturer remuneration to their group health plan clients, effective for plan years beginning after August 3, 2028. The same law makes PBMs report gross and net drug spend, rebates, and spread-pricing details to large self-funded employers semi-annually, or quarterly on request.
In January 2026, the Department of Labor issued proposed rules that would expand PBM compensation disclosures to plan fiduciaries, following an April 2025 executive order. None of this fixes your analytics platform. It makes the problem larger: the more rebate dollars that flow into your plan by law, the wider the gap between the gross-cost reports you manage on and the net-cost reality you fund. Plans that build net-cost discipline now will be ready when the reporting lands. Plans that don't will be reconciling years of mispriced renewals under a spotlight.
What Actually Needs to Change
You keep the pass-through contract. What has to change is how you treat it: stop running it as a purely financial transaction and start engineering your data infrastructure to speak net cost as a first language. Three changes matter most:
- Demand a rebate-allocation feed from your PBM. A handful of transparent PBMs can already deliver a monthly file tying rebate dollars back to individual claims. If yours can't, you're flying on instruments with half the gauges covered. Insist on a claim-level net-cost field appended to every transaction.
- Build net-cost views into your analytics. Every PMPM report, every specialty trend dashboard, every high-cost claimant review should toggle between gross and net. Your stop-loss submission should go to market with both numbers, backed by a clear audit trail. Let underwriters price the real risk, not the inflated one.
- Push for point-of-sale integration. The smartest plans are piloting arrangements where negotiated rebate estimates reduce the cost calculation at the pharmacy counter. It means the member's coinsurance or deductible is based on something closer to the plan's actual economic exposure from the start, not months later in a reconciliation nobody ever does.
Net Cost Needs to Be the Default Setting
Right now, pass-through is a financial concept bolted onto a data system that runs on gross numbers. That quarterly check feels like a win, and it is - but if it's not fully integrated into how you measure, project, and price your plan's drug spend, you're managing in a hall of mirrors. The reflection looks fine until you walk straight into a wall.
Make net cost your single source of truth. Every report, every forecast, every member transaction should bend toward what the plan actually pays. Then pass-through becomes the smarter health plan you bought in the first place.