PBM “Lesser of Logic”: What It Is, How It’s Used, and What to Do About It
In pharmacy benefits, PBM “lesser of logic” determines how much the plan pays for a drug. On paper, it’s designed to protect the payer by ensuring the plan always pays the lowest price among a set of benchmark options. But PBMs often game the logic by controlling which benchmarks are included in the first place.
What Is “Lesser of Logic”?
It’s a pricing rule that compares multiple benchmarks for a drug claim and uses the lowest one to calculate plan cost. Typically, these benchmarks include:
Benchmark Type | Description |
AWP – Discount | Average Wholesale Price minus a fixed % discount |
MAC Price | Maximum Allowable Cost set by the PBM |
U&C (Usual & Customary) | The pharmacy’s cash price |
Copayment | The member’s cost share |
Ingredient Cost + Dispensing Fee | Pass-through model element |
The logic should apply to all of these and select the lowest price for the third-party payer. But here’s where the manipulation starts.
Benchmark | Value |
AWP – 16% | $112 |
MAC Price | $85 |
U&C | $92 |
Copayment | $10 |
Ingredient Cost + Dispensing Fee ($2) | $87 |
Plan pays: $75 (MAC Price)
Rationale: It’s the lowest of all benchmarks.
Same drug, same benchmarks, but the PBM contract excludes U&C pricing from the “lesser of” calculation.
Benchmark | Value |
AWP – 16% | $112 |
MAC Price | $85 |
U&C | $60 (excluded from logic) |
Copayment | $10 |
Ingredient Cost + Dispensing Fee ($2) | $87 |
Plan pays: $75 (ingredient cost only)
Plan Should have paid: $50
PBM pockets: $25 spread (assuming no dispensing fee spread 🙄)
Problem: U&C was excluded, despite being the lowest actual price.
Caveat Emptor: Copayments Must Be Part of “Lesser of” Logic
The member’s copayment isn’t just a flat fee. It’s supposed to be the maximum they pay. If the ingredient cost is less than the copay, the member should pay the lesser amount. But PBMs often skip this check, allowing the member to overpay while the plan pays nothing. The technical term for this process is called a clawback.
Example:
- Ingredient Cost: $8
- Member Copay: $10
- Proper Charge to Member: $8
- Charge to Plan: $0
- Total Paid: $8
- Overpayment if Copay Isn’t Adjusted: $2
- Who Keeps the $2? PBM or pharmacy, depending on contract setup
This is a quiet but common form of margin capture. It punishes members and undermines trust in the plan.
Fix: Require in your contract that member cost share be the lesser of:
- Flat copay
- Coinsurance amount
- Total claim cost (ingredient + fee)
That one line can stop millions in overpayments across large populations.
How PBMs Justify the Exclusion
They may say U&C data is unreliable or inconsistent. In other cases, they quietly stop collecting or enforcing U&C pricing, allowing it to fade out of relevance.
Why This Matters
Over thousands of claims, this tactic inflates your drug spend without raising red flags. You’re led to believe you’re paying the lowest price, but you’re often not.
What You Can Do About It
- Review your PBM contract. All four benchmarks, AWP – %, MAC, U&C, and copayment must be included in the lesser of logic.
- Request sample claims data. Spot-check random NDCs across pharmacies. Look for cases where U&C is lower than what was paid.
- Demand transparency. Know how often MAC lists are updated and whether U&C is captured and audited.
- Work with a fiduciary PBM. One that passes through all discounts and aligns its compensation with your best interest.
Final Thought
Lesser of logic only works if it includes every relevant benchmark. If your PBM gets to pick and choose, they’re not protecting you, they’re protecting their margin. Learn about lesser of logic and more at the Pharmacy Benefit Institute of America (PBIA) Summit.