PBM Audit-Safe Pharmacy Days' Supply Calculator
Days'-supply errors on insulin, eye drops and inhalers are the largest single source of PBM audit recoupments. Run the arithmetic with your PBM's own conversion values, and keep the audit note with the fill record.
Why Days' Supply Fails PBM Audits (and the Formula That Survives One)
Every mode is the same audit logic: days = floor(total dispensable amount ÷ amount used per day), then capped by the manufacturer beyond-use date. The audit failures come from the conversion values, not the division: PBMs audit eye drops against their own drops-per-mL figure and insulin against priming-inclusive daily use. PAAS National's eye-drop audit guidance and NCPA audit-prevention training both centre on exactly these two conversions (your PBM manual's current figures control).
| Mode | Numerator | Denominator |
|---|---|---|
| Tablets/capsules | Quantity dispensed | Units taken per day (SIG) |
| Insulin pens/vials | Total units dispensed | Injected units/day + priming units × injections/day |
| Eye/ear drops | mL × your PBM drops/mL × bottles | Drops/dose × eyes × doses/day |
| Inhalers | Labelled actuations × canisters | Puffs per day (SIG) |
KX modifier threshold: have you crossed $2,480 this year?
For CY 2026 the KX threshold is $2,480 for PT and SLP combined and $2,480 separately for OT (CMS Therapy Services CY 2026 update; re-confirmed at each November re-check). Crossing it is not a cap and not permission: append KX only on claims where continued therapy is medically necessary and the record documents it. The year-to-date fields in the allocator above run this check on every calculation.
Frequently Asked Billing Questions
Why does this calculator ask me for drops per mL instead of using a standard number?
Because there is no single standard: each PBM audits against its own published drops-per-mL estimate, and solutions vs suspensions differ. Shipping one hidden number would manufacture audit failures; the manual value for the plan you are billing controls.
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