How 340B works, one drug at a time.
The program looks abstract described in policy language. Followed through a single vial from manufacturer to patient, every obligation becomes concrete — and it becomes obvious where programs break.
At a glance
- 01Parties involved
- 4
- 02Common model
- Replenishment
- 03Registration windows
- Quarterly
- 04Where it breaks
- Eligibility & accumulation
Manufacturer to patient, and back again
01Manufacturer
Sells at the 340B ceiling price
02Wholesaler / Distributor
Applies the discount at purchase
03Covered Entity
Hospital, health center or clinic
04Contract Pharmacy
Dispenses to the patient
05Patient
Receives the prescribed drug
Supporting participants
S1
HRSA / OPA
Program oversight, audits
S2
Medicaid
Duplicate-discount prevention
S3
PBMs / Payers
Adjudicate the claim
S4
TPA / 340B Software
Administers split billing
The critical thing to understand is that in most hospital settings, 340B is a replenishment model rather than a physical inventory model. The drug given to the patient was not itself bought at the 340B price. It is dispensed from regular stock, the dispense is recorded as 340B-eligible, and a replacement unit is later purchased at 340B pricing. This is why accumulator accuracy matters so much.
Everything hinges on how the dispense is evaluated.
Registration, treatment and dispensing are largely mechanical. The moment the split billing system decides whether a dispense is 340B-eligible is where accuracy actually gets tested — get that wrong, and either savings disappear silently or a diversion finding follows.
Eight steps, four of which are where things go wrong
- 01
Manufacturer agrees
A manufacturer signs a Pharmaceutical Pricing Agreement with HHS. In exchange for Medicaid and Medicare Part B coverage, it agrees to sell covered outpatient drugs to covered entities at or below the 340B ceiling price.
- 02
Entity registers
The covered entity registers in HRSA OPAIS during one of four annual windows, listing every eligible site and any contract pharmacy arrangements, and making its Medicaid billing election.
- 03
Patient is treated
An eligible patient receives care from the entity. Eligibility depends on the entity's written patient definition — the relationship, the provider, the location and the documentation.
- 04
Drug is dispensed
The drug is dispensed from existing stock, at an entity pharmacy or a contract pharmacy. Physically, nothing about this dispense is yet a 340B transaction.
- 05
Dispense is evaluated
The split billing system tests the dispense against the eligibility rules — patient, provider, location, payer — and either accumulates it into virtual 340B inventory or does not. This is the single highest-leverage point in the entire process.
- 06
Replenishment is ordered
Once enough accumulated units exist, a replacement package is ordered at the 340B price through the entity's 340B purchase account. Accumulation that never converts into an order is savings that never arrived.
- 07
Claim is billed
The entity bills the payer at its normal contracted rate. For Medicaid, the billing pathway must match the Medicaid Exclusion File status and any state-specific identifier requirement, or a duplicate discount occurs.
- 08
Everything is documented
Eligibility evidence, accumulation records, reconciliation, exception resolution and oversight documentation. At audit, an undocumented correct action and an incorrect action look identical.
Where each step breaks in practice
01Registration
- Common failure
- Site operating before registration is effective
- Consequence
- Purchases for that site are ineligible; the period cannot be recovered
02Patient eligibility
- Common failure
- Patient definition applied inconsistently, or referral documentation missing
- Consequence
- Diversion finding — the most common category of adverse finding
03Accumulation
- Common failure
- Provider or location not mapped correctly in the split billing system
- Consequence
- Under-accumulation, which produces no error and no alert — just lost savings
04Accumulation
- Common failure
- Eligibility logic broader than the written policy
- Consequence
- Over-accumulation, which is diversion and does produce a finding
05Replenishment
- Common failure
- Accumulated units never converted into 340B orders
- Consequence
- Savings earned on paper and never realized in cash
06Medicaid billing
- Common failure
- MEF status does not match actual billing practice
- Consequence
- Duplicate discount — a finding with repayment consequences
07Documentation
- Common failure
- Correct practice with no evidence trail
- Consequence
- Treated at audit as though it did not happen
How 340B works — common questions
01What is virtual inventory?
A software-maintained record of how many units of each drug have been dispensed to 340B-eligible patients but not yet replaced with 340B-priced stock. When the accumulated quantity reaches a full package size, a 340B order can be placed. It is an accounting construct, not a physical shelf.
02What is the difference between the replenishment model and a physical inventory model?
In a physical model, 340B drugs are purchased, stored and dispensed separately from other stock. In a replenishment model, everything is dispensed from common stock and eligible dispenses are tracked so that replacement units can be purchased at 340B pricing. Most hospital programs use replenishment; some clinic and grantee settings use physical inventory.
03Who decides whether a patient is eligible?
The covered entity does, through its written patient definition policy — but that policy must be consistent with HRSA guidance and applied uniformly. Auditors test practice against the entity's own policy, so a policy that is broader than practice and one that is narrower both create problems.
04How long does the whole cycle take?
From dispense to accumulated replenishment order is typically days to weeks depending on volume. From a compliance perspective the more important cycle is reconciliation and oversight, which should run on a monthly or quarterly cadence and be documented.
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