Products where days’ supply is hard to calculate
- Insulin and other injectables, where the dose, the priming amount and the package size all matter.
- Inhalers, where the number of actuations per device and the dose per use determine how long it lasts.
- Eye and ear drops, where the number of drops per bottle varies by product.
- Creams, ointments and other topicals, where the amount used per application is often not stated.
- Medications taken “as needed”, where the directions need a stated maximum to calculate a days’ supply.
- Products that come only in a fixed package size, such as kits or pens.
How to document the calculation
- Calculate days’ supply from the prescriber’s directions, not from a habit or a default in the pharmacy system.
- Where directions are unclear, clarify them with the prescriber and record the clarification on the prescription.
- For hard-to-measure products, note how you calculated the days’ supply, for example the dose per use and the amount per package.
- When a product comes only in a fixed package size, note why the full package was dispensed.
Spot-check before any audit
Pick a small set of recent claims for the products above and compare the days’ supply billed with the directions and the quantity dispensed. Fix the workflow behind any mismatch you find, so the same issue does not repeat. Our audit documentation checklist lists the other records auditors usually request.
Build days’ supply checks into the workflow
The most reliable fix is a consistent process rather than a one-time cleanup. Agree on how the pharmacy calculates days’ supply for each hard-to-measure product, write it down in a short reference sheet, and keep the sheet at the dispensing stations. Ask the pharmacist who verifies each prescription to confirm that the days’ supply matches the directions before the claim is submitted. When the plan rejects or adjusts a claim because of days’ supply, record what happened and why, and update the reference sheet if needed. Reviewing a few of these records each month shows whether the process is working and gives you examples to use in staff training.
Frequently asked questions
What is days’ supply on a pharmacy claim?
The number of days the quantity dispensed should last when the patient takes it as directed.
Why do auditors focus on days’ supply?
Because it affects refill timing and plan limits, and because a mismatch between the directions, the quantity and the days’ supply billed is easy to see in the records.
How should I calculate days’ supply for insulin?
Work from the prescribed dose, the amount used for priming where that applies, and the package size, and record how you calculated it. Check the manufacturer’s information and the plan’s rules for the product.
Can a days’ supply finding be disputed?
If the records show the calculation followed the directions, you can explain it in your response with the supporting documents. No outcome is guaranteed.
Official sources
Talk to Pharma360
Want a second look at how your pharmacy calculates days’ supply? Pharma360 offers audit readiness reviews by phone and Zoom. See our audit readiness & mock audits service, call (267) 809-2396, or request a call back. Your first phone or Zoom consultation is free, one time. Philadelphia-based, serving independent pharmacies in all 50 states.
Published by Pharma360 Solutions LLC · Updated . General information for pharmacy owners, not legal advice. Deadlines and requirements are set by your PBM contract and audit notice; always check the notice.