Prescription drug coverage sits at the center of most employer-sponsored health plans. But how plans manage medication costs often stays hidden from employees. The system hinges on a list called a formulary, paired with a tiered cost-sharing model that balances access, clinical effectiveness, and cost control. That matters for HR leaders, brokers, and employees, especially as pharmacy spending keeps rising.
Plans classify medications into groups, then apply different levels of patient cost-sharing, such as copays, coinsurance, or deductibles, based on that classification. The goal is to steer patients toward effective, affordable options while still covering necessary treatments.
What Is a Formulary?
A formulary is a regularly updated list of drugs a health plan, a pharmacy benefit manager (PBM), or a self-funded employer will cover. It's not a one-and-done document. Plans revise formularies quarterly, or more often as new drugs launch, safety data shifts, and price negotiations happen. A pharmacy and therapeutics committee, made up of physicians and pharmacists, reviews drugs for safety, effectiveness, and cost before deciding what gets covered, at what tier, and under what rules.
Most formularies are structured into tiers, each with a different cost-sharing obligation for the patient:
- Tier 1 (Generic Drugs): Lowest copay. Chemically identical to brand-name drugs but much cheaper. Plans encourage generic use whenever available.
- Tier 2 (Preferred Brand Drugs): Moderate copay. Brand-name drugs selected by the plan or PBM as cost-effective, often due to negotiated discounts or rebates.
- Tier 3 (Non-Preferred Brand Drugs): Higher copay or coinsurance. Patients pay more to access these, unless a medical necessity exception is granted.
- Tier 4 (Specialty Drugs): Highest cost-sharing, often coinsurance. Covers high-cost biologics, injectables, and chronic condition drugs like rheumatoid arthritis, multiple sclerosis, or cancer. Few prescriptions but roughly half of total drug spend.
Formularies can be open (covering most drugs with varied cost-sharing) or closed (excluding some drugs unless an exception is approved). Closed formularies have grown more common as plans concentrate purchasing to negotiate better prices.
How Prescription Drug Coverage Actually Works
When an employee fills a prescription, the pharmacy submits a claim to the PBM or health plan. The plan checks the patient's formulary tier, benefit design, and any prior authorization or step therapy requirements. The employee pays the calculated cost-share, and the plan pays the remainder (after discounts and rebates).
Several mechanisms shape coverage:
Prior Authorization (PA)
Some high-cost or risky drugs need approval before the plan pays. The plan confirms the drug is medically necessary and that cheaper options weren't overlooked. The prescriber submits documentation.
Step Therapy
Step therapy, or 'fail first,' means patients try cheaper, effective drugs before the plan pays for pricier alternatives. Common for hypertension, diabetes, and acid reflux.
Quantity Limits
Plans cap how much drug you can get per month, such as a 30-day supply, to prevent waste. Exceptions need a doctor's sign-off.
Exclusion Lists
Some drugs aren't covered at all: lifestyle meds, unapproved treatments, or drugs with over-the-counter equivalents. Patients pay full price unless an exception is approved.
The Employer's Strategic Role in Managing Drug Costs
Employers who self-fund their health plans have more control over pharmacy benefits. They can design formularies, negotiate directly with PBMs, or replace the PBM entirely with a model like WellthCare Pharmacy™, which eliminates spread pricing and aligns incentives with employee health. For fully insured employers, the carrier manages the formulary, but the employer still bears the cost through future premium increases.
A well-managed formulary is a win-win: employees pay less for effective drugs, and employers avoid waste on costly ones with no extra benefit. The catch is that traditional PBM contracts can hide fees, rebate flows, and spread pricing that eat savings, and until recently plan sponsors had little legal leverage to see those numbers.
Fiduciary Duties and the 2026 PBM Transparency Rules
ERISA plan fiduciaries have long owed a duty to pay only reasonable compensation for plan services. Pharmacy contracts made that duty hard to meet, because gag clauses and confidential terms kept plan sponsors from seeing what PBMs actually earned. Congress began removing those barriers with the Consolidated Appropriations Act, 2021, which barred gag clauses and required brokers and consultants to disclose their compensation to plan fiduciaries.
The rules tightened in 2026. In January 2026, the Department of Labor proposed a rule requiring PBMs to give self-insured plan fiduciaries semiannual, drug-level disclosures of pricing, manufacturer remuneration, and spread. Then Congress passed the Consolidated Appropriations Act, 2026, signed into law on February 3, 2026, which puts PBM compensation under federal statutory disclosure standards, strengthens fiduciary audit rights, and adds rebate pass-through requirements. For HR and finance leaders, the practical effect is that PBM compensation is no longer a black box. Fiduciaries now have both the right and the duty to see what the plan pays and what the PBM keeps.
Common Employee Questions About Formularies
- What if my drug isn't on the formulary? Ask your prescriber to submit a medical necessity request. If approved, the plan covers the drug, typically at the cost-sharing level for non-preferred drugs.
- Can my drug shift to a higher tier mid-year? Yes, formularies change. Many plans notify members in advance and let existing patients stay on the current tier for a transition period while they and their prescriber evaluate options.
- How do I check my plan's formulary? Check your benefit portal, the PBM's website, or ask HR. Review it each open enrollment.
- Does the formulary affect my health? It can, if it pushes people away from needed drugs. A good formulary doesn't block essential therapies. Look for a plan with an evidence-based list.
Why HR and Benefits Leaders Should Care
Prescription drug costs are the fastest-growing component of employer health spending, often outpacing medical inflation. Pharmacy accounts for more than a quarter of employer health care dollars. A bad pharmacy benefit means higher claims, lower adherence, and unhappy employees. A well-designed formulary, one that pushes prevention, generics, and transparency the way WellthCare™ does, cuts total care costs and improves employee health.
Modern benefit systems now blend pharmacy coverage with preventive care incentives and Health-to-Wealth™ programs. WellthCare, for example, pairs its pharmacy model with a system where verified preventive actions earn reward dollars at the WellthCare Store™, and employers commit savings to employees' retirement accounts. That shifts the focus from cost control to value creation, aligning employer and employee interests.
Prescription drug coverage is more than a list of copays. Managed well, it cuts claims, boosts health, and builds employee wealth. The formulary is the roadmap, and smart benefits leaders make sure that roadmap leads to better outcomes, not just cheaper ones.
This article is for general information only and is not legal, tax, or medical advice. Employers should consult their own advisors.