A locum tenens arrangement lets your practice bill a substitute physician’s work as though your own physician performed it. Medicare calls the paid version a fee-for-time compensation arrangement and tags the claim with modifier Q6. The substitute can cover your patients for no more than 60 continuous days, and the record behind those claims has to survive a review years later.
What this covers
- Reciprocal billing takes modifier Q5. Fee-for-time compensation, the arrangement CMS used to call locum tenens, takes Q6 after the procedure code in item 24D.
- Medicare caps the substitute at a continuous period of no more than 60 days, and the period keeps running through days the substitute does not work.
- The claim carries the regular physician’s NPI in item 24J. The substitute’s NPI belongs in your file, not on the claim.
- Entering Q6 certifies the record exists and is open to inspection. A false certification can bring fraud penalties and revocation under 42 CFR 424.535.
- The rule is written for physicians. Nurse practitioners, physician assistants and psychologists cannot be billed under Q6.
The 60-day clock is not a break between two assignments. It runs through the quiet weeks.A continuous period of covered visits ends when the regular physician returns to work.
Two arrangements, two modifiers
Chapter 1 of the Medicare Claims Processing Manual gives each arrangement its own section. Section 30.2.10 covers reciprocal billing. Section 30.2.11 covers fee-for-time compensation, the arrangement formerly called locum tenens. CMS dropped that label because section 16006 of the 21st Century Cures Act used locum tenens arrangements to mean both, and Transmittal 3774 rewrote both sections on June 13, 2017.
| Arrangement | How the substitute is paid | Modifier |
|---|---|---|
| Fee-for-time compensation | Per diem or similar fee-for-time payment, as an independent contractor | Q6 |
| Reciprocal billing | Nothing required. Two physicians cover for each other occasionally | Q5 |
The difference is the payment arrangement, not the paperwork. Reciprocal arrangements need not be in writing. Fee-for-time work requires the per diem payment, so the substitute is a paid contractor.
The conditions Medicare lists
Both sections list the same conditions. Read them as the list a reviewer runs against your claim later.
- The regular physician is unavailable to provide the services.
- The beneficiary has arranged, or seeks, to receive the services from that regular physician.
- For Q6, the regular physician pays the substitute on a per diem or similar fee-for-time basis.
- The substitute does not provide services to Medicare patients over a continuous period longer than 60 days, unless the regular physician is called to active duty.
- The claim carries Q5 or Q6 after the procedure code, in item 24D of the CMS-1500 or the electronic equivalent.
Covered visit service is broad. It includes the substitute’s visits and anything furnished incident to the physician’s services. Post-operative visits inside a surgical global fee are the exception, because the practice is already paid the global fee.
One limit comes from MAC guidance rather than the manual. Noridian states that the provisions apply only to physicians, and that services of nurse practitioners, physician assistants and CRNAs may not be billed under either arrangement.
How the 60-day clock actually runs
The manual defines a continuous period of covered visit services. It starts on the first day the substitute provides covered visit services to your Medicare Part B patients and ends on the last day the substitute provides them before the regular physician returns to work. It continues without interruption on days the substitute does not work, and it keeps running if a second substitute covers during the same absence.
| Date | What happens | Billable under Q6 |
|---|---|---|
| June 30 | The regular physician goes on vacation | Not applicable |
| July 2 | The substitute’s first visit, so the period starts | Yes |
| August 30 | Day 60 of the period | Yes |
| August 31 | Day 61 | No |
| September 2 | The substitute’s last visit, and the period ends | No |
The manual’s own example works out this way. Sixty days from July 2 lands on August 30, so services from August 31 through September 2 fall outside the arrangement. The practice bills through August 30, and the substitute bills the rest in their own name.
A gap in the schedule, a change of substitute or a relabeled payer contract does not restart the 60 days. A new period begins only after the regular physician returns to work. When a physician leaves the practice and the group hires a temporary replacement, the group may bill for up to 60 days.
The record that carries the certification
Filing the modifier is a statement of fact. The manual says entering Q6 or Q5 certifies that the services were covered visit services furnished by the substitute named in the regular physician’s record, that the record is available for inspection, and that the practice is entitled to submit the claim.
- The manual requires a record of each service the substitute provided, kept with the substitute’s NPI and made available to the MAC on request.
- Noridian states that the information does not have to appear on the claim form, so your file is the only place the substitute exists.
- A false certification can carry civil or criminal fraud penalties, or administrative penalties including revocation of billing privileges under 42 CFR 424.535.
Build the file while the assignment is live. A defensible one answers these questions:
- The regular physician’s absence dates, and the first and last dates the substitute covered.
- Each date of service, patient, procedure code and modifier billed.
- The substitute’s name, NPI and state license number.
- The per diem invoice and payment record for fee-for-time work.
- The signed agreement, even a one page letter, dated before the first service.
Group claims: who is the performing provider
When a group bills, the claim describes the group rather than the substitute. Section 30.2.13 states that where an entity bills for an independent substitute under a reciprocal or fee-for-time arrangement, the performing physician on the claim is the regular physician who is a member of the entity. The group’s NPI goes in 33a and the regular physician’s NPI in 24J.
| Claim field | What it carries | Whose number |
|---|---|---|
| Item 24D | The procedure code with Q5 or Q6 appended | No number field |
| Item 24J | The performing physician for that line | The regular physician’s NPI |
| Item 33a | The billing entity | The group’s NPI |
| Practice file | The record of each service the substitute furnished | The substitute’s NPI |
The group section adds a condition that catches practices off guard. To bill in the name of the regular physician, the substitute may not have reassigned the right to Medicare payment to the group through a CMS-855R reassignment enrollment form approved by the MAC. A physician covered this way stays off the group’s enrollment file.
CMS has stated that locum tenens physicians are not required to be enrolled in the Medicare program, and payment is made in the name and billing number of the practice that engaged them. State licensure and hospital privileges still apply.
Where the arrangement stops working
The most common misuse of Q6 is putting it on a claim for a provider the rule does not cover. The fee-for-time and reciprocal rules are written for physicians, which MAC guidance defines as MDs and DOs. Congress added one exception, effective June 13, 2017, for physical therapists furnishing outpatient therapy in a health professional shortage area, a medically underserved area or a rural area.
That distinction lands hard in behavioral health. A practice covering a psychologist’s leave, a BCBA’s absence or a counselor’s vacation cannot put Q6 on the claim, because those practitioners are not physicians and the therapy exception does not reach them. The substitute must be credentialed with the payer and bill under their own NPI, which makes coverage a credentialing question rather than a modifier choice.
Payers run their own versions. Providence Health Plan’s reimbursement policy for locum tenens and reciprocal billing tracks the Medicare requirements across its commercial, Medicare and Medicaid lines. Ohio Medicaid publishes Q6 as substitute practitioner (locum tenens), and the Montana Medicaid physician manual sets the same 60-day cap.
A payer can ask for documentation the Medicare manual never mentions, or refuse the arrangement outright. Read the payer’s provider manual before the assignment starts, not after the first denial arrives.
Locum tenens and modifier Q6 questions
Q6 identifies a service furnished under a fee-for-time compensation arrangement, which CMS used to call locum tenens. The regular physician or group appends it after the procedure code in item 24D of the CMS-1500. Payment is made as though the regular physician performed the service.
Q5 signals a reciprocal billing arrangement, where physicians cover for each other and no per diem payment is required. Q6 signals fee-for-time compensation, where the regular physician pays the substitute on a per diem or similar basis as an independent contractor. Both carry the same 60-day limit.
It begins on the first day the substitute provides covered visit services to the regular physician’s Medicare Part B patients, and ends on the last day the substitute provides them before the regular physician returns to work. In the manual’s example the period ran July 2 through September 2, and only services through August 30 were billable.
Services past day 60 cannot be billed under the regular physician’s number. The substitute either bills in their own name and billing number or reassigns payment to whoever bills for them. A new continuous period can begin once the regular physician returns to work.
CMS has said no, because payment goes to the regular physician or group rather than to the substitute. State licensure, hospital privileges and payer-specific credentialing still apply. Confirm the current position with your MAC before relying on it for a long assignment.
No. MAC guidance states that these provisions apply only to physicians, and names nurse practitioners, physician assistants and CRNAs as providers whose services cannot be billed this way. The 2017 exception covers physical therapists furnishing outpatient therapy in a shortage, underserved or rural area.
The bottom line
Modifier Q6 is not a shortcut around credentialing delays. It pays for a substitute physician’s work during the regular physician’s absence, for no more than 60 continuous days, and only when the record can be produced. Get the arrangement, the modifier and the file right, and the claims pay as though your physician saw the patient.
Is there a file behind your locum claims?
We review fee-for-time and reciprocal billing for practices that use substitute physicians, check the modifier and the 60-day window claim by claim, and rebuild the service record so it holds up under review. See how our medical billing team handles this work, then send one assignment’s claims and the schedule behind them.
Request a free locum tenens billing reviewThis article describes Medicare fee-for-service policy in the Medicare Claims Processing Manual and MAC guidance. Commercial payer contracts, state Medicaid programs and managed care plans set their own rules for substitute providers.
