Pharmacy Benefit Management for Employer Health Plans: How to Control Prescription Drug Costs

Pharmacy costs now represent 25 to 30 percent of total health plan spend for most employer groups, and that share is growing faster than any other component of medical costs. The entity responsible for managing those costs is the pharmacy benefit manager, known as a PBM, which operates between your health insurance plan and the pharmacies your employees use. Most mid-market employers have almost no visibility into how their PBM contract works, what the PBM earns from drug manufacturers, or whether the pricing in their contract favors the employer or the intermediary. That gap in understanding is costing employers real money on every renewal cycle.

What a Pharmacy Benefit Manager Actually Does

A pharmacy benefit manager is the administrative and financial layer between your group health plan and the retail or mail-order pharmacies your employees visit. On the surface, PBMs handle logistics: they verify eligibility when an employee presents a prescription, apply your plan's cost-sharing rules, and pay the pharmacy. But the more consequential work happens upstream, in the contracts PBMs negotiate with drug manufacturers and pharmacy networks before a single prescription is ever filled.

PBMs negotiate volume-based rebates with drug manufacturers in exchange for preferred placement on the formulary, which is the list of drugs your plan covers at each tier. They negotiate network rates with pharmacies that determine what your plan pays per prescription. They design and manage the formulary tiers that shape what employees pay at the pharmacy counter. And they operate specialty pharmacy subsidiaries that manage the most expensive medications in your plan.

For a fully insured employer, the PBM is typically bundled into the health plan contract and almost entirely invisible. The carrier manages the PBM relationship, and the employer sees only aggregate pharmacy cost data at renewal. For employers in self-funded or level-funded arrangements, the relationship can be structured differently, with more direct access to claims data, contract terms, and rebate reporting.

How PBM Contracts Are Structured

PBM arrangements fall into three broad models, each with different implications for employer cost visibility.

Bundled (carrier-managed): The most common arrangement for mid-market employers. Your health carrier has a PBM relationship, often with a subsidiary or exclusive partner, and the PBM terms are embedded in your carrier contract. You have limited ability to negotiate PBM terms separately, and rebate information is typically reported only in aggregate, if at all.

Carved-out: The employer contracts directly with a standalone PBM, separate from the medical plan. This is more common in large employer and self-funded contexts. Carve-outs give employers more direct control over formulary design, network selection, and rebate reporting, but they also require more administrative oversight and coordination between the medical and pharmacy plans.

Transparent or pass-through: The PBM charges a flat administrative fee per claim, passes manufacturer rebates directly to the employer, and bills the actual acquisition cost for drugs rather than a marked-up contract rate. Transparent PBMs have gained traction as employer demand for cost accountability has increased, particularly among groups with high specialty drug utilization.

The Rebate Transparency Problem

Drug manufacturers pay PBMs to ensure their products receive preferred formulary placement, typically a Tier 2 or preferred brand position rather than a non-preferred Tier 3 position. These payments, called rebates, represent billions of dollars flowing through the PBM industry each year. For branded drugs with significant commercial market share, rebates can represent 30 to 50 percent of the drug's list price.

In traditional PBM contracts, the employer either receives a small portion of these rebates as a per-member-per-month credit, or does not receive them at all. The PBM retains the balance as compensation for managing the formulary and rebate programs. Because rebate terms are typically confidential, employers have no way to evaluate whether they are receiving a fair share of the rebate pool generated by their plan's prescription volume.

The practical impact is significant. A mid-market employer with 50 employees might be generating $80,000 to $150,000 in annual rebates through their pharmacy plan. Under a traditional bundled arrangement, most of that money flows to the PBM or carrier with minimal pass-through. Under a transparent contract, most of it would return directly to the employer. The difference can offset a meaningful portion of annual premium increases without any change in plan design or employee benefits.

Spread Pricing and Its Impact on Employer Costs

A second transparency issue involves spread pricing. In a spread pricing arrangement, the PBM charges the employer one rate for a prescription and pays the dispensing pharmacy a lower rate, retaining the difference as margin. For a generic drug where the pharmacy acquisition cost might be $3, the PBM might bill the employer $11 and pay the pharmacy $4, keeping $7 as undisclosed compensation.

Spread pricing is legal and common in bundled PBM contracts. It is typically not disclosed as a separate line item, meaning employers cannot see it in standard claims reporting. The ERISA disclosure requirements that apply to brokers and advisors do not fully reach PBM spread practices, leaving employers with limited options short of contract renegotiation or transition to a transparent model.

For employers evaluating PBM arrangements, requesting an ingredient cost audit, where actual pharmacy acquisition costs are compared against billed amounts, is the most direct way to quantify spread exposure in an existing contract. Brokers with pharmacy benefit expertise can request this analysis as part of a renewal review.

Specialty Drug Spending: The Fastest-Growing Cost Driver

Specialty medications, including biologic therapies for autoimmune conditions, oncology treatments, and high-cost gene therapies, now represent 40 to 50 percent of total pharmacy spend for typical employer groups, despite being used by fewer than 5 percent of plan members. For a 50-person employer group, a single employee starting a biologic therapy for rheumatoid arthritis or Crohn's disease can add $50,000 to $200,000 in annual pharmacy costs almost immediately.

Because specialty drug costs are highly concentrated and highly unpredictable, they create substantial volatility in employer health plan costs from year to year. A group that has no specialty utilization in one plan year may face dramatically different costs the next year, driving renewal increases that seem disconnected from any change in overall employee health status. This volatility is one reason why specialty drug management has become a central component of sophisticated employer benefits strategy.

Managing specialty drug exposure is one of the most important levers mid-market employers have for controlling long-term pharmacy costs. The tools available include prior authorization requirements that verify clinical appropriateness before a specialty drug is approved, step therapy protocols that require trying lower-cost alternatives before approving higher-cost drugs, and stop-loss coverage that caps employer exposure on individual high-cost cases. For self-funded groups, specialty drug riders and carve-out specialty management programs offer additional protection against catastrophic single-member pharmacy costs.

Site of Care Optimization for Specialty Drugs

A frequently overlooked opportunity for specialty medication cost control is site of care. Many biologic therapies are administered by infusion, and the cost of the same infusion can vary by a factor of five to ten depending on whether it happens at a hospital outpatient facility, a freestanding infusion center, or in the patient's home. Hospital outpatient facilities typically bill the highest rates because they apply a facility fee structure that layers additional charges on top of the drug acquisition cost.

For employers with direct data access, analyzing infusion site utilization and implementing benefit design changes that steer members toward lower-cost settings can reduce specialty drug costs by 20 to 35 percent on those claims without any change in the therapy itself. This requires coordination between the PBM, the medical plan, and a utilization management program, but the savings potential makes it worth the effort for groups with meaningful specialty utilization. A home infusion benefit or an infusion center preferred designation in the plan design are practical levers many mid-market employers have not yet used.

Key Performance Metrics Every Employer Should Track

Most employers receive some form of pharmacy reporting at renewal, but it often presents aggregate cost totals rather than the performance metrics that would enable meaningful evaluation of the PBM contract. Three metrics matter most for mid-market employers trying to assess whether their current PBM arrangement is performing well.

Generic dispensing rate (GDR): The percentage of total prescriptions filled with generic drugs rather than brand equivalents. For a well-managed employer plan, GDR should be 85 percent or higher. A GDR below 80 percent suggests the formulary is not effectively steering members toward generics, or that step therapy and prior authorization protocols are not being enforced consistently. Low GDR is one of the most reliable indicators of an underperforming PBM arrangement.

Specialty drug percentage of total pharmacy spend: Specialty drugs as a percentage of total drug costs. For a mid-market employer group, a specialty percentage above 55 percent warrants a review of specialty management protocols. Employers who can identify which conditions are driving specialty costs and whether appropriate management programs are in place are far better positioned to control future spend than those who see only aggregate totals.

Rebate pass-through rate: What percentage of manufacturer rebates is the employer actually receiving? In a fully transparent contract, 100 percent of rebates pass through at point of sale or shortly after. In a typical bundled arrangement, the effective pass-through rate might be 20 to 40 percent of total rebates generated, with the balance retained by the PBM or carrier.

Metric	Target Benchmark	Warning Level
Generic Dispensing Rate	85% or higher	Below 80%
Specialty as % of Drug Spend	Under 50%	Above 55%
Rebate Pass-Through Rate	90%+ (transparent model)	Under 40% (bundled)
Administrative Fee per Claim	$2.50 to $5.00	Above $8.00
Network Penetration Rate	90%+ of claims in network	Below 85%

The Health Funding Projector allows employers to model how changes in pharmacy cost assumptions affect total plan funding needs over a 3-year horizon. Using current GDR, specialty percentage, and rebate data as inputs gives a more accurate picture of forward-looking pharmacy cost trends than applying a flat medical trend factor to last year's pharmacy spend.

Evaluating Your Current PBM Arrangement

Most mid-market employers cannot easily renegotiate their PBM contract because it is embedded in a carrier relationship with terms they did not negotiate separately. But even within a bundled arrangement, there are steps employers can take to improve transparency and reduce unnecessary costs before the next renewal cycle.

Start with a data request. Ask your broker or carrier for the following items: total pharmacy claims by tier (generic, brand, specialty); generic dispensing rate; rebate amount credited to your plan over the past 12 months; specialty drug spend as a percentage of total pharmacy spend; and the top 10 drugs by cost to the plan. If any of these data points are unavailable or presented only in formats that obscure the underlying metrics, that is itself a meaningful finding about the transparency of your current arrangement.

Then benchmark. Compare your GDR, specialty percentage, and rebate pass-through against market standards for a group of similar size and industry. Significant deviations from benchmarks indicate either an above-average utilization pattern, which requires a clinical management response, or an underperforming PBM contract, which requires a contractual response. The two require different actions, and conflating them leads to the wrong solution.

When to Consider a PBM Carve-Out

For employers in level-funded health plans or self-funded arrangements, carving out the pharmacy benefit from the medical plan and contracting directly with a transparent standalone PBM is an option worth evaluating when specialty drug costs are high, rebate transparency is poor, or the employer has sufficient claims data to model the cost of alternatives accurately.

A carve-out introduces coordination complexity between the medical and pharmacy plans. Prior authorizations for specialty drugs, accumulator adjustment programs that track deductible and out-of-pocket progress, and high-cost case management all require communication between two separate plans rather than one. For groups where specialty drug spend is a material cost driver, however, the rebate recapture and spread pricing elimination available through a transparent PBM typically more than offset the administrative overhead.

The timing of a PBM change should align with health plan renewal to avoid mid-year disruption for employees. Employers considering a carve-out should begin the evaluation process 6 to 9 months before their renewal date to allow adequate time for vendor review, contract negotiation, formulary design, and employee communication.

Connecting PBM Strategy to Your Broader Health Plan Structure

The practical ability to act on PBM data depends significantly on how your health plan is funded. Fully insured employers have limited access to detailed claims data and limited ability to negotiate PBM terms independently. They are largely dependent on what the carrier provides, which typically means limited rebate transparency and no ability to conduct an independent ingredient cost audit.

Employers in self-funded arrangements have contractual access to claims data under ERISA and can use that data to evaluate PBM performance, request contract amendments, or conduct competitive PBM reviews. The utilization management programs administered by the TPA are often the primary mechanism for enforcing prior authorization and step therapy requirements that prevent unnecessary specialty drug costs.

The Benefits ROI Calculator can help quantify the financial value of pharmacy cost control initiatives, comparing the one-time cost of a PBM audit or transition against projected savings over a 3-year period. For most mid-market employers, the return on a serious PBM review is measured in multiples of the investment, particularly when specialty drug trends are factored into the projection.

Related Reading

For additional context on controlling health plan costs for mid-market employer groups, explore these related Benefitra articles:

• Stop-Loss Insurance for Self-Funded Employers: Specific Coverage, Aggregate Limits, and Laser Exclusions Explained
• Level-Funded Health Plans: The Middle Ground Between Fully Insured and Self-Funded
• Utilization Management for Employer Health Plans: Controlling Costs Without Cutting Coverage
• Third-Party Administrators for Self-Funded Health Plans: What Mid-Market Employers Need to Know

Frequently Asked Questions

Can a mid-market employer negotiate PBM terms directly?

In a fully insured plan, PBM terms are embedded in the carrier contract and are generally not negotiable by the employer independently. In a self-funded or level-funded arrangement, employers or their third-party administrator can sometimes negotiate individual plan features like formulary tier placements or mail-order incentives, but fully transparent PBM access typically requires moving to a self-funded structure with a direct PBM contract or a pass-through TPA model.

What is the difference between a rebate and a discount in a PBM contract?

A discount reduces the amount the plan pays at point of sale, appearing as a lower ingredient cost in claims data and visible in standard reporting. A rebate is a payment from a drug manufacturer back to the PBM after the claim is processed, typically tied to volume thresholds. Discounts are visible in claims data; rebates are not unless the contract explicitly requires rebate reporting by line item. In transparent contracts, both discounts and rebates flow to the employer. In traditional bundled contracts, rebates are often retained by the PBM with minimal pass-through to the plan sponsor.

How much can employers realistically save by improving PBM transparency?

Savings depend on current rebate pass-through rates, specialty drug utilization levels, and spread pricing exposure in the existing contract. Employers transitioning from a traditional bundled PBM to a fully transparent model commonly report savings of 10 to 20 percent on total pharmacy spend. For a 50-person group spending $150,000 per year on pharmacy, that translates to $15,000 to $30,000 in annual savings. Groups with above-average specialty utilization often see proportionally larger savings because manufacturer rebates for specialty drugs are substantially larger on a per-claim basis than for retail medications.

Should pharmacy costs be included in stop-loss coverage?

For self-funded employers, pharmacy costs are typically included in the aggregate stop-loss calculation and may also be included in specific stop-loss calculations for individual high-cost cases. Employers with employees on high-cost biologic therapies should verify exactly how those costs are treated under their specific and aggregate stop-loss thresholds and whether any laser exclusions apply to known high-cost members at renewal. A specialty drug rider can provide additional protection for groups with significant biologic therapy utilization that is not adequately covered by standard stop-loss terms.

What should employers ask at their next renewal about pharmacy costs?

Four questions give employers the most useful information at renewal. First, what is our current generic dispensing rate and how does it compare to industry benchmarks for groups of similar size? Second, what percentage of our total pharmacy spend is driven by specialty medications and which therapeutic categories are the primary cost drivers? Third, what rebates did our plan generate last year and what percentage was passed through to us? Fourth, does our current plan include prior authorization and step therapy requirements for specialty drugs, and how are those requirements being enforced? The answers to these four questions will tell an employer more about their PBM arrangement than any amount of aggregate premium data.