Incident-to Billing: What Does Incident To Mean in Medicare Billing?

Incident-to billing is Medicare’s rule that lets a physician (or another billing practitioner) bill for services that auxiliary personnel furnish, including nurses, physician assistants and nurse practitioners, as if the physician performed them, when the service is an integral part of the physician’s own plan of care, happens in the office, and is directly supervised.

The phrase sounds like legal language, and the original version of this article said so. Thirteen years later the core rule is the same. One thing has changed: how supervision can happen.

Where you see it

Place	What goes there
CMS-1500 box 24J, 837P loop 2310B	The supervising physician’s NPI as rendering provider, not the NP, PA or nurse who furnished the service
CMS-1500 box 17 and 17b	The ordering or supervising practitioner, with qualifier DQ for supervising, where the MAC asks for it
Remittance advice	Paid at 100 percent of the fee schedule allowed amount rather than 85 percent; the only visible sign on the remit
Medicare Physician Fee Schedule	PC/TC indicator 5 marks codes covered incident to a physician’s service when auxiliary staff provide them; 96413 (chemotherapy infusion) is one

The requirements

Medicare Benefit Policy Manual, Chapter 15, section 60, lists four conditions. All of them must hold for every service billed incident to.

Requirement	What it means in the office
Integral, although incidental, part of the physician’s professional service	The service belongs to a course of treatment the physician personally began. The physician performed the initial service and sees the patient often enough to show “active participation in and management of the course of treatment.”
Commonly rendered without charge or included in the physician’s bill, and of a type commonly furnished in physicians’ offices	Injections, dressing changes, follow-up visits on an established plan, supplies like gauze and ointments. Not services a physician office would not ordinarily provide.
Furnished by the physician or by auxiliary personnel under the physician’s direct supervision	Auxiliary personnel can be employees, leased employees or independent contractors of the practice. The supervising physician must be able to reassign to the billing entity.
An expense to the practice	The practice pays for the staff time and the supplies. A drug the patient bought elsewhere is not billable, though administering it is.

Two limits matter as much as the four conditions:

• Setting. For physician billing, incident to applies in a noninstitutional setting, meaning anywhere other than a hospital or skilled nursing facility. In a hospital outpatient department the hospital bills incident to services on its own claim; the physician’s claim carries only the physician’s own work.
• Who. “Physician” here also means a PA, NP, clinical nurse specialist, nurse midwife or clinical psychologist billing under their own benefit, at their own rate.

Direct supervision, and what changed in 2026

Direct supervision has never meant the same room. It means the supervising physician is “present in the office suite and immediately available to provide assistance and direction throughout the time the aide is performing services.” A physician at the hospital across town, or reachable only by phone, does not meet it.

The CY 2026 Physician Fee Schedule final rule (CMS-1832-F, issued October 31, 2025, effective January 1, 2026) permanently adopted a definition of direct supervision that allows the supervising practitioner to be immediately available “through real-time audio and visual interactive telecommunications (excluding audio-only).” CMS applied this to incident to services under 42 CFR 410.26, except services with a global surgery indicator of 010 or 090. In plain terms: for most incident to services, a physician on a live video connection now counts as present; a physician on the phone still does not. A practice that relies on video presence should write down when it will and will not.

Who may bill, and the 85 percent alternative

How the service is billed	Who signs the claim	Medicare’s allowed amount
Incident to, every requirement met	the supervising physician, as rendering provider	100 percent of the fee schedule amount
Under the NPP’s own NPI	the NP, PA or CNS	85 percent of the fee schedule amount (Claims Processing Manual, Chapter 12, sections 110 and 120)
Incident to an NPP’s service	the NPP	85 percent

Only the supervising practitioner may bill an incident to service. Billing at 85 percent is not an error. It is the correct choice whenever any incident to element is missing: a new patient, a new problem that changes the plan, a physician out of the suite and not on video. The claim still goes out the same day; only the rendering NPI and the allowed amount change.

Oncology examples

Situation	Bill as
Nurse gives a leuprolide injection in the office; physician in the suite seeing other patients	drug J-code plus administration, incident to under the physician
Chemotherapy infusion 96413 in a freestanding infusion suite; physician in the suite	incident to under the physician (indicator 5 code)
NP sees an established patient for a follow-up visit on the plan the oncologist set; oncologist in the suite	9921x incident to under the oncologist
Same visit, but the patient has a new complaint and the NP starts a new medication	9921x under the NP’s own NPI at 85 percent
Any of the above in a hospital-based clinic (POS 22)	the physician’s claim carries only physician work; the hospital bills the rest
Weekly on-treatment visit during a radiation course	not an incident to question at all: the visit is bundled into 77427

Worked example: one follow-up visit, two ways

A nurse practitioner sees an established patient for a 99213 visit. The 2026 national non-facility value of 99213 is 2.85 RVUs, about 95.19 at the 33.4009 conversion factor. National figures before geographic adjustment and sequestration; illustrative.

Billed as	Allowed	Medicare 80 percent	Patient 20 percent
Incident to under the physician (requirements met)	95.19	76.15	19.04
Under the NP’s own NPI (85 percent)	80.91	64.73	16.18

The difference is 14.28 per visit. Over a full NP schedule the difference is large, which is why auditors review incident to claims.

What to do

• Decide the rendering NPI at check-in, not at billing. If the physician is not in the suite today, or the visit is a new patient or a new problem, the NP’s NPI goes on the claim. A clear rule at check-in prevents corrections later.
• Document the four things a reviewer asks for. The physician’s initial note and plan; the NP’s or nurse’s signed note tied to that plan; evidence the physician was in the suite or on live video (the schedule, a co-signature, a supervision log); and physician visits frequent enough to show continued management.
• Do not bill incident to from a hospital department. POS 21, 22 and 23 claims carry physician work only.
• Post the 85 percent lines as paid, not short-paid. The difference between the 85 percent allowed and your fee is a CO-45 contractual adjustment, not a balance to chase.
• Expect reviews, not denials. Incident to errors are found in post-payment review and repaid with interest; there is no CARC that says “physician was not in the suite.”
• Iridium Suite’s claim scrubber applies payer-specific rules at charge entry, which is where a practice can add its own check for an NPP visit billed under a physician’s NPI.

Related terms

• Rendering provider vs billing provider
• NPI numbers
• Place of service codes
• POS 22, outpatient hospital
• Facility vs non-facility rates
• CPT 77427, radiation treatment management

Further reading: CMS Medicare Benefit Policy Manual, Chapter 15, section 60; CMS Medicare Claims Processing Manual, Chapter 12, sections 110 and 120 (PA, NP and CNS payment); CMS fact sheet: CY 2026 Physician Fee Schedule final rule; First Coast: Incident-to service guidelines.