If you take Humira or an adalimumab biosimilar and you have employer-sponsored health insurance, the cost you pay may have very little to do with the drug itself — and everything to do with decisions your HR department and PBM made in a room you were never in.
Research published in 2025 by Nomi Health found that the same adalimumab biosimilar varies from $639 to $2,655 per script across different self-funded employer health plans. That's a 4x price difference for the same FDA-approved medication, from the same manufacturer.
Here's why this happens — and what you can do about it.
How Self-Funded Employer Plans Work
Most large employers don't buy health insurance in the traditional sense. Instead, they self-fund their health benefits — they pay claims directly out of their own funds, and hire a third-party administrator (often a large insurance company or PBM) to manage the benefit.
The key implication: a self-funded employer has more direct control over their drug formulary than a fully-insured employer does. They can negotiate directly with PBMs, include or exclude specific drugs, set different tiers, and structure cost-sharing however they want — within legal limits.
This flexibility is the reason costs vary so dramatically. Two employers using the same PBM can have very different adalimumab costs based on the contract terms their benefits team negotiated.
Why Most Employers Don't Know What They're Paying
Here's the uncomfortable part: many self-funded employers don't actually know what they're paying for specific drugs, because PBMs don't have to tell them.
PBM contracts often include:
- Bundled pricing that obscures per-drug costs
- Confidential rebate arrangements where the PBM keeps a share of manufacturer rebates without passing them to the employer
- Spread pricing where the PBM charges the employer more than it pays the pharmacy, keeping the difference
The result is that an HR benefits manager at a 500-person company may genuinely not know that their plan pays $2,200/month for a biosimilar that a competitor down the street pays $700 for.
What This Means for Employees
For employees, the variation shows up as:
- Deductible burn rate: If you have a high-deductible plan, a higher-priced formulary means you spend down your deductible faster on adalimumab
- Coinsurance exposure: If your plan uses percentage coinsurance for specialty drugs (e.g., 30% of drug cost), a higher plan cost means your 30% is larger
- Out-of-pocket maximum timing: Your path to your plan's out-of-pocket maximum is faster with higher drug costs, which matters for everything else you might need
The net result: two employees with identical plan structures but different employers can pay substantially different amounts for the same medication, through no decision of their own.
What You Can Do as an Employee
Understand your specific plan's adalimumab coverage. Log in to your insurer's portal and look up your specific adalimumab product. What tier is it on? What's the coinsurance rate? Is there a preferred biosimilar with different cost-sharing?
Ask HR explicitly. Ask your HR or benefits department whether the plan has a preferred adalimumab product — and whether using a different biosimilar would reduce your cost-sharing.
Request a plan document review. Under ERISA, employees have the right to access their Summary Plan Description (SPD) and plan documents. These documents specify how specialty drugs are covered.
Consider using a copay card. If you're commercially insured, manufacturer copay cards (Humira Complete at $5/month, or biosimilar equivalents) cap your out-of-pocket regardless of what the plan pays the pharmacy. This is the single most impactful tool for reducing your personal exposure.
If you're approaching your deductible or OOP max mid-year, the timing of your fills matters. A prescription filled a day before your OOP max is hit costs very differently than one filled the day after.
What Employers Should Know
If you're an HR or benefits professional reading this: PBM transparency is increasingly achievable through contract negotiation. Specifically:
- Require pass-through pricing for specialty drugs — the employer pays the pharmacy rate, not a spread
- Require full rebate pass-through — manufacturer rebates flow back to the plan, not to the PBM
- Use a specialty pharmacy network that reports per-drug acquisition costs
- Request a specialty drug spend report by NDC number annually
The variation in biosimilar pricing across self-funded plans is largely a contracting problem, not a market problem. Employers with transparent PBM contracts consistently pay less.
This article contains general information about employer health benefit structures. It does not constitute legal or financial advice. Plan structures and costs vary significantly; verify your plan's specific terms through your HR department or plan documents.