What Documentation Wins a MAC Appeal (and Why So Many Get Denied)

You are making a single factual claim in a MAC appeal: the drug cost me more to buy than you paid me to dispense it. The PBM will not take your word for it. The proof is a dated wholesaler or manufacturer invoice showing your per-unit acquisition cost for that NDC, as of the date you filed. Without it, there is nothing to adjudicate, and most PBMs will simply close the appeal as incomplete.

One detail trips pharmacies up constantly: the acquisition cost you submit usually must be net of rebates and discounts and limited to the drug’s ingredient cost — not your shelf cost, not including service fees. OptumRx’s submission guidance, for example, states the per-unit cost must be net of any supplier or manufacturer rebates and discounts and limited to the drug ingredient cost, excluding pharmacy service fees. Submit a gross number and you hand the PBM a clean reason to deny.

Have all of this ready before you file. Missing any one of these is a common cause of an incomplete-appeal denial:

1. Pharmacy NCPDP / NPI
2. BIN / PCN for the claim
3. Prescription or claim number
4. Date of fill / date of service
5. 11-digit NDC of the exact product dispensed
6. Per-unit acquisition cost — net of rebates/discounts, ingredient cost only
7. The supporting invoice — dated wholesaler/manufacturer invoice proving that cost as of filing
8. Wholesaler or manufacturer name
9. Any required attestation — some PBMs/states require a signed attestation of the acquisition cost (and sometimes of GPO/wholesaler ownership interest)

Even complete appeals are denied at high rates, but most denials trace to a handful of fixable causes:

• The filing window closed. Windows are short and they vary by PBM and by state — some PBM manuals require filing within roughly seven business days of the original claim. (That’s a PBM-manual-specific figure, not a universal legal deadline — confirm your own PBM’s window and your state’s rule.) File late and the merits never get read.
• The acquisition cost isn’t documented properly. No invoice, the wrong format, or a cost that isn’t stated net of discounts.
• The drug “isn’t on the MAC list.” The PBM argues the claim was priced on a non-MAC basis and therefore falls outside the MAC appeal process. (Some states define MAC broadly — as any term a PBM uses to set reimbursement — specifically to close this loophole.)
• Prospective-only repricing. The PBM updates the price going forward but doesn’t pay back the loss you already took on the dispensed claim — so a “granted” appeal can still leave that fill underwater.
• NDC-availability denial. The PBM denies the appeal asserting the drug is available at or below its price from a national or regional wholesaler, and (in many states) must name the NDC and source. That denial is itself useful information — it tells you where the PBM thinks you can source the drug.

How often are appeals denied? The clearest public data comes from Washington State’s drug price transparency program, which recorded pharmacies filing roughly 145 appeals per day across 2018–2020, with about 99.3% of those appeals denied by PBMs. That’s Washington-specific and self-reported by PBMs, but the direction is unambiguous: a sloppy appeal is a denied appeal. Clean documentation is the entire game.

A successful appeal generally means the PBM corrects the MAC and lets you reverse and rebill the claim. The two things worth knowing:

• Retroactive vs. prospective. Stronger state rules require the correction to apply retroactively to the date of service; weaker ones only fix the price going forward. Know which you’re owed before you accept the outcome.
• Similarly situated pharmacies. In a number of states, a successful appeal must be applied to all similarly situated network pharmacies — so one win can quietly correct the price for everyone. Confirm whether your state requires similarly-situated application.

• Document at the moment of the spike. Keep the dated invoice that shows your elevated cost on the fill date; don’t reconstruct it weeks later.
• File inside the window. Calendar the deadline the day you spot an underwater claim.
• Submit the acquisition cost the way the PBM defines it — net of discounts, ingredient cost only.
• Work the recurring offenders first. The same handful of NDCs and payers tend to go underwater repeatedly; that’s where documentation effort compounds.

If you’d rather not assemble all of this by hand for every claim, MarkupRx flags your underwater NDCs against NADAC and assembles the appeal documentation for you. You can also see the below-NADAC pattern for your state in our public explorer, no login: see your state. For the end-to-end process and deadlines, see the full appeal process, and for why the gap exists in the first place, reimbursed below NADAC.