Pharmacy Law Lowdown: Defending Against PBM Inventory Audits

On paper, an inventory audit is simple: what a pharmacy bought against what it billed. In practice, however, attorneys say that pharmacy benefit managers (PBMs) control the audit period, the approved suppliers, and the national drug code (NDC) matching in ways that can turn a surplus into a shortfall.

“An inventory audit should be simple, comparing what a pharmacy bought, in terms of the amount of a product, versus what the pharmacy billed for that product. If it's zero, no shortage; if it's minus, then there's a shortage; if there's plus, there's a surplus,” said Dae Lee, PharmD, Esq, CPBS, shareholder at Buchanan Ingersoll & Rooney. “It's simple math. However, unfortunately, PBMs create the inventory audit to be more complicated than what it should be, to their advantage.”

In the October rendition of Pharmacy Law Lowdown, Lee and co-host Lucas Morgan, Esq, shareholder at Buchanan Ingersoll & Rooney, explain how PBMs run inventory audits. As PBMs compare a pharmacy’s drug purchases with its billed claims, Morgan and Lee describe how audit periods, wholesaler accreditation requirements, and NDC mismatches can lead PBMs to claw back the full amount paid on those claims.

They urge pharmacies to keep detailed purchasing records, learn their state’s audit protections, and dispute every audit finding, however small, to protect their PBM contracts.

READ MORE: PBM Audits Demand Pharmacy Awareness, Compliance, and Proactive Defense

Sourcing Traps and Timing Discrepancies

Although PBMs frame audits as routine measures to eliminate fraud, experts highlight how technical traps routinely turn legitimate inventory into massive clawback liabilities. A primary vulnerability stems from strict PBM restrictions on approved drug wholesalers.

PBMs often enforce narrow definitions requiring purchases strictly from National Association of Boards of Pharmacy (NABP)-accredited distributors or specific authorized trading partners. Lee and Morgan point to Masters RX, a reputable McKesson subsidiary that holds proper accreditation yet faces claim denials when PBMs classify it as noncompliant for certain products.

Timing rules create additional inventory shortfalls. PBM auditors typically evaluate a fixed 12-month window and restrict inventory lookbacks to 30 days prior to the audit start date. Consequently, drugs acquired 45 or 60 days prior to the audit window to capture bulk discounts are frequently excluded from inventory totals, generating artificial shortages.

Similar audit exposure occurs when pharmacies purchase remaining drug stock from closing pharmacies. According to an analysis, despite peer transfers being lawful under federal supply chain standards, PBM auditors heavily penalize non-wholesaler invoices due to minor documentation gaps.¹

Furthermore, minor NDC mismatches, such as dispensing an equivalent covered generic under a slightly different code, frequently result in complete reimbursement clawbacks despite zero financial harm to the payer.

High-Risk Triggers and Regulatory Consequences

PBM audit selection is rarely random, relying heavily on targeted operational metrics. In a previous discussion with Harini Bupathi, Esq, partner practicing in Frier Levitt’s Life Sciences practice group, she emphasized that pharmacies located in designated urban heat zones or those exhibiting outlier dispensing volumes face frequent reviews. Recent industry recaps confirm that auditors aggressively target high-reimbursement categories, including diabetic testing supplies, specialty drugs, controlled substances, and glucagon-like peptide-1 (GLP-1) medications.²

The stakes, however, extend far beyond immediate monetary recoveries. Today, PBMs function as de facto regulators whose detailed transaction records directly inform State Board of Pharmacy inspections and enforcement priorities. Furthermore, an uncollected audit penalty creates a dangerous domino effect across a pharmacy's operations.

When one PBM issues a network termination over unaddressed findings, the pharmacy must disclose that action during re-credentialing with other plan sponsors. This requirement often triggers secondary audits, cross-network terminations, and severe damage to community standing.²

Legislative Protections and Proactive Defense

To counter aggressive clawbacks, independent pharmacies can leverage emerging state and federal legal protections. Many state fair audit laws explicitly forbid PBMs from recovering funds for clerical errors or code mismatches in the absence of actual financial harm.³

Legal precedents validate these statutory shields, as demonstrated when independent pharmacies in Rhode Island successfully challenged unlawful audit clawbacks enforced by Prime Therapeutics.

Federal oversight has also expanded significantly following the enactment of the Consolidated Appropriations Act of 2026. Legal guidance highlights that this federal legislation establishes Any Willing Pharmacy protections under Medicare Part D, creates essential retail pharmacy designations for underserved areas, and bans spread pricing structures starting in 2028. In addition, the law subjects PBMs to direct federal audit scrutiny, increasing transparency around recovered funds.³

Legal experts urge pharmacists to transition from reactive responses to proactive compliance strategies. Pharmacies should execute regular internal self-audits to verify wholesaler credentials and patient copay collection records. Crucially, legal advisors emphasize disputing every single audit finding, regardless of the dollar amount involved, to safeguard provider contracts and maintain network participation.

Be sure to tune into Drug Topics for important updates in pharmacy law and how to handle them from hosts Dae Lee, PharmD, Esq, CPBS, and Lucas Morgan, Esq, shareholders at Buchanan Ingersoll & Rooney, a national law firm that provides legal, business, regulatory, and government relations advice to a wide range of clients. All episodes of Pharmacy Law Lowdown will be available in video format via Drug Topics on the last Wednesday of each month. Check out our most recent episode here: Pharmacy Law Lowdown: FDA’s Evaluation of Peptides.

REFERENCES

1. Hartkopf E. PBM audit risk when purchasing inventory from a closing pharmacy. Pharmacy Audit Assistance Service National. Accessed October 27, 2026. https://paasnational.com/pbm-audit-risk-when-purchasing-inventory-from-a-closing-pharmacy/

2. Lee DY. PBMs as de facto regulators: a 2025 recap of PBM audits and their growing impact on board of pharmacy enforcement. Buchanan Ingersoll & Rooney. December 12, 2025. Accessed October 27, 2026. https://www.bipc.com/pbms-as-de-facto-regulators-a-2025-recap-of-pbm-audits-and-their-growing-impact-on-board-of-pharmacy-enforcement

3. National PBM reforms enacted in 2026: what independent pharmacies need to know. Barclay Damon. February 10, 2026. Accessed October 27, 2026. https://www.barclaydamon.com/alerts/national-pbm-reforms-enacted-in-2026-what-independent-pharmacies-need-to-know