Two denial patterns
CO-97 — bundled service: a separately billable procedure is paid as part of the visit because the modifier is missing or wrong. The work was done; the revenue disappears into the base code.
CO-B7 — provider not certified: supervision rules vary by state and payer, and enrollment status decides who may bill. A nurse practitioner who isn't enrolled with a payer, or is billing under the wrong arrangement, gets denied regardless of how clean the claim is.
How we prevent them
- Modifier and bundling checks on every claim with add-ons
- NP enrollment with Medicare (PECOS), Medicaid and commercial panels
- Group linkage, Tax ID and location set up correctly
- Effective dates confirmed in writing before you bill
- Supervising-provider arrangements checked against each contract
Billing under your own NPI or incident-to
A nurse practitioner can usually bill Medicare under their own NPI, paid at 85% of the physician fee schedule. Incident-to billing under a supervising physician pays the full rate, but only when Medicare's conditions are met — including an established plan of care and direct supervision — and billing incident-to when they aren't is a compliance risk, not a billing shortcut. Commercial and Medicaid plans set their own rules. We check which applies to each visit and each payer, and say so in writing.
State practice rules and credentialing
States differ on whether nurse practitioners practise independently or need a collaborative or supervisory agreement, and payers may ask for that agreement during credentialing. NPs who prescribe controlled substances need a DEA registration for each state they practise in. We collect the agreements and registrations once, track their expiry dates, and enroll each NP individually with Medicare through PECOS, with Medicaid and with commercial panels.