When Modifier SA Goes on an NP's Claim, and Who Requires It

Does modifier SA belong on your own claim?

Not usually. Modifier SA is published in the HCPCS Level II set with the long descriptor "Nurse practitioner rendering service in collaboration with a physician," and its record carries an effective date of July 1, 2001 1Ref 1Centers for Medicare & Medicaid Services (CMS) (2026).October 2026 Alpha-Numeric HCPCS File.The verbatim HCPCS Level II long descriptor for modifier SA, 'Nurse practitioner rendering service in collaboration with a physician', and the 2001-07-01 effective date carried on its record in the October 2026 Alpha-Numeric HCPCS File. Used only for what the modifier means, not for who requires it.. It exists to mark a claim on which the practitioner who rendered the service and the practitioner being billed are different people. Bill under your own NPI and that gap does not exist, so there is nothing for SA to declare.

Whether SA becomes a requirement anywhere is a payer question, and the answer is set program by program. Texas Medicaid requires it in one narrowly drawn case, described below. New York's Medicaid nurse practitioner manual lays out how NP claims are paid and states no SA requirement. Neither of those is your answer unless you bill that program.

So the thing to settle first is whose NPI the claim goes out under.

What Medicare does with modifier SA

Nothing. Medicare's rules for nurse practitioner services never ask for modifier SA. Part B covers your services when a list of conditions is met, one of which is that you perform them while working in collaboration with a physician 2Ref 2Office of the Federal Register / Centers for Medicare & Medicaid Services (2026).§ 410.75 Nurse practitioners' services..The Medicare Part B coverage condition at 42 CFR 410.75(c)(3) that an NP performs services while working in collaboration with a physician, and the clarification at (c)(3)(iii) that the collaborating physician need not be present or independently evaluate each patient. Used to show the collaboration requirement is a coverage condition carrying no modifier instruction., and that is a coverage condition rather than a coding instruction. CMS's billing guidance for advanced practice registered nurses tells you to bill under your NPI and names exactly one modifier: AS, for assistant-at-surgery services 3Ref 3Centers for Medicare & Medicaid Services (2026).Advanced Practice Registered Nurses (APRNs).CMS's own APRN billing guidance: bill under the NP's NPI, report only modifier AS for assistant-at-surgery services, and the payment arithmetic of 80 percent of the lesser of the actual charge or 85 percent of the physician fee schedule amount outside a hospital or SNF. Also used, as an absence only, for the fact that modifier SA appears nowhere in that guidance..

The collaboration condition is thinner than the word suggests. The same regulation says the collaborating physician does not need to be present when you furnish the service, and does not need to independently evaluate every patient you see 2Ref 2Office of the Federal Register / Centers for Medicare & Medicaid Services (2026).§ 410.75 Nurse practitioners' services..The Medicare Part B coverage condition at 42 CFR 410.75(c)(3) that an NP performs services while working in collaboration with a physician, and the clarification at (c)(3)(iii) that the collaborating physician need not be present or independently evaluate each patient. Used to show the collaboration requirement is a coverage condition carrying no modifier instruction.. What your state requires of that relationship, including whether a collaborative agreement or protocol has to exist on paper, is a separate question answered by your board rather than by a claim form.

Payment does not turn on the modifier either. Medicare pays an NP 85% of the physician fee schedule amount. Outside a hospital or skilled nursing facility, that works out as 80 percent of the lesser of the actual charge or that 85 percent 3Ref 3Centers for Medicare & Medicaid Services (2026).Advanced Practice Registered Nurses (APRNs).CMS's own APRN billing guidance: bill under the NP's NPI, report only modifier AS for assistant-at-surgery services, and the payment arithmetic of 80 percent of the lesser of the actual charge or 85 percent of the physician fee schedule amount outside a hospital or SNF. Also used, as an absence only, for the fact that modifier SA appears nowhere in that guidance.. The arithmetic runs with nothing appended to the line.

But absence is not prohibition. Nothing in the sources read for this article says Medicare rejects SA on an NP's claim; the payment rules and CMS's guidance simply never ask for it. If a Medicare Administrative Contractor publishes an article instructing otherwise for a particular service, that article governs that claim, and the date and article number are worth keeping with your billing notes.

Where SA is required: Texas Medicaid, on the physician's claim

On somebody else's claim, in a narrow case. Texas Medicaid's handbook for medical and nursing specialists requires modifier SA on each claim detail when a physician bills under the physician's own NPI for a service a nurse practitioner or clinical nurse specialist provided, and the physician made no decision about the client's care or treatment on the same date of service as the billable medical visit 4Ref 4Texas Health and Human Services Commission / Texas Medicaid & Healthcare Partnership (TMHP) (2026).Texas Medicaid Provider Procedures Manual, Vol. 2, Provider Handbooks: Medical and Nursing Specialists, Physicians, and Physician Assistants Handbook.Texas Medicaid only: the requirement that a physician billing under the physician's own NPI submit modifier SA on each claim detail where the physician made no decision about the client's care on the same date of service; the sibling modifiers U7 and SB; the 92 percent NP and CNS rate under 1 TAC 355.8281 with its lab, X-ray and injection carve-out; and that an NP billing directly uses their own individual NPI. September 2026 edition..

The party billing in that rule is the physician. An NP billing Texas Medicaid directly for services the NP performed uses their own individual NPI 4Ref 4Texas Health and Human Services Commission / Texas Medicaid & Healthcare Partnership (TMHP) (2026).Texas Medicaid Provider Procedures Manual, Vol. 2, Provider Handbooks: Medical and Nursing Specialists, Physicians, and Physician Assistants Handbook.Texas Medicaid only: the requirement that a physician billing under the physician's own NPI submit modifier SA on each claim detail where the physician made no decision about the client's care on the same date of service; the sibling modifiers U7 and SB; the 92 percent NP and CNS rate under 1 TAC 355.8281 with its lab, X-ray and injection carve-out; and that an NP billing directly uses their own individual NPI. September 2026 edition., and SA belongs to the other claim, the one carrying a physician's number over a nurse practitioner's work.

SA also sits inside a small set a billing physician chooses among: SA when the service was provided by an NP or clinical nurse specialist, U7 for a physician assistant, SB for a certified nurse midwife 4Ref 4Texas Health and Human Services Commission / Texas Medicaid & Healthcare Partnership (TMHP) (2026).Texas Medicaid Provider Procedures Manual, Vol. 2, Provider Handbooks: Medical and Nursing Specialists, Physicians, and Physician Assistants Handbook.Texas Medicaid only: the requirement that a physician billing under the physician's own NPI submit modifier SA on each claim detail where the physician made no decision about the client's care on the same date of service; the sibling modifiers U7 and SB; the 92 percent NP and CNS rate under 1 TAC 355.8281 with its lab, X-ray and injection carve-out; and that an NP billing directly uses their own individual NPI. September 2026 edition.. The set shows what the modifier is for: it names the discipline that rendered the service, nothing more.

Texas sets the rate separately, in rule rather than through the modifier. Under 1 TAC 355.8281 the Texas Medicaid rate for NPs and CNSs is 92 percent of the rate paid to a physician for the same professional service, and 100 percent of the physician rate for laboratory services, X-ray services and injections 4Ref 4Texas Health and Human Services Commission / Texas Medicaid & Healthcare Partnership (TMHP) (2026).Texas Medicaid Provider Procedures Manual, Vol. 2, Provider Handbooks: Medical and Nursing Specialists, Physicians, and Physician Assistants Handbook.Texas Medicaid only: the requirement that a physician billing under the physician's own NPI submit modifier SA on each claim detail where the physician made no decision about the client's care on the same date of service; the sibling modifiers U7 and SB; the 92 percent NP and CNS rate under 1 TAC 355.8281 with its lab, X-ray and injection carve-out; and that an NP billing directly uses their own individual NPI. September 2026 edition.. That rate attaches to who you are. No source read here ties a payment change to the presence or absence of the modifier itself.

The edition read for this article is the September 2026 handbook, and the manual is revised monthly. Check the current edition before relying on any line of it.

Why the answer changes at the state line

Because federal Medicaid law hands the definition back to the states. The regulation defining nurse practitioner services describes them as furnished by a registered nurse who meets a State's advanced educational and clinical practice requirements, if any, beyond basic nursing education 5Ref 5Centers for Medicare & Medicaid Services, HHS (2026).§ 440.166 Nurse practitioner services..The federal Medicaid definition of nurse practitioner services, which turns on a State's own advanced educational and clinical practice requirements. Used for the structural reason claim-level conventions such as modifier SA are set program by program rather than nationally.. When the qualifications are set state by state, the claim conventions built on top of them are too, and modifier SA is one of those conventions rather than a national rule.

New York runs the same service through a different door. Its Medicaid nurse practitioner policy guidelines, version 2022-1, state that the services of nurse practitioners are reimbursable directly to the enrolled nurse practitioner, and that the collaborating physician is identified by name, license number and Medicaid Identification Number on the NP's enrollment application 6Ref 6New York State Department of Health, Medicaid Program (2022).New York State Medicaid Program: Nurse Practitioner Manual — Policy Guidelines.New York Medicaid only: that NP services are reimbursable directly to the enrolled nurse practitioner and that the collaborating physician's name, license number and Medicaid Identification Number are filed with the enrollment application rather than carried on the claim. Its silence on modifier SA is reported as silence and not as a prohibition.. The relationship is recorded once, at enrollment, instead of being re-declared on every claim.

That manual states no SA requirement. That is silence rather than a ban: it does not say New York forbids the modifier, and a later transmittal or a managed-care plan operating in the state can carry an instruction the 2022 manual does not.

Two states, two mechanisms, and neither one is the national rule.

Declaring an NP's involvement to a payer is a different obligation from declaring it to a patient. Whether your state requires signage telling patients you are not a physician is a practice-act question, and it lives nowhere near the claim form.

How to find the rule your payer applies

Go to the manual that governs the claim and search it for the modifier. For a state Medicaid program that means the discipline-specific provider manual: New York's Medicaid provider manual page for nurse practitioners, to take one, carries a Nurse Practitioner Fee Schedule, an Enhanced Program Fee Schedule, a procedure code list and NP billing guidelines in one place 7Ref 7eMedNY (New York State Department of Health Medicaid fiscal agent) (2026).Provider Manuals - Nurse Practitioner.New York only, and as the worked example of the lookup method: a state Medicaid program publishes a discipline-specific nurse practitioner provider manual carrying a fee schedule, an enhanced program fee schedule, a procedure code list and NP billing guidelines in one place. Used for the shape of where a state's NP claim rules live, not for any figure.. Most state programs publish some version of that document under a name of their own.

Three moves get you the rest of the way.

• Establish whose NPI sits in the rendering field before looking at modifiers at all. If it is yours, most SA questions dissolve there.
• Search the manual for the two characters together with the word modifier, then read the surrounding paragraph rather than the table row. The condition that triggers the modifier is usually in the prose.
• If the manual is silent, put the question to the payer's provider representative in writing and keep the reply with its date. A written answer is what you will want if the claim is reviewed two years from now.

If you are moonlighting as a 1099 NP inside somebody else's practice, the group's contract with that payer controls the claim, and the modifier question belongs to whoever holds that contract. Ask before the first date of service rather than after the first remittance.

Before you add a modifier, check the identifiers

Check the identifiers first. A claim can be returned for reasons that have nothing to do with a modifier, and the identifiers are where a solo practice commonly finds them: the rendering NPI, the billing NPI, the enrollment record the payer matches against, and whether the correct 363L taxonomy code is attached to that enrollment. Adding a modifier to a claim failing for one of those reasons changes nothing and hides the cause.

For an NP billing under their own NPI, the working default is to append only what a manual asks for, and to write down which manual, which edition and which date was checked. A modifier appended on a hunch is an assertion about who did the work, and it is durable: it sits in the claim history long after the reason for it is forgotten.

If a payer's written answer conflicts with the manual you found, raise the conflict with the payer in writing before the next claim goes out rather than absorbing it as a rule. Where enough money rides on the reading, confirm it with a coder or with counsel who works that payer.