For qualifying Medicare locum tenens arrangements, the regular physician or eligible physical therapist can bill for covered services provided by a substitute provider. The claim uses the regular provider’s billing information and the Q6 modifier to identify the service as furnished under a fee-for-time compensation arrangement. The substitute provider’s NPI must also be kept in the required records.
What Is Locum Tenens Billing?
Locum tenens billing allows a regular provider to receive Medicare Part B payment for covered services furnished by a temporary substitute during the regular provider’s absence. The regular provider pays the substitute on a per diem or similar fee-for-time basis.
Common reasons for temporary coverage include illness, vacation, pregnancy, continuing medical education, or another period when the regular provider is unavailable. The arrangement helps patients continue receiving care without treating the substitute as the permanent provider for billing purposes. If you need broader context on how temporary coverage is structured, see our locum staffing model guide.
For Medicare, this is a specific billing framework. It does not mean a practice can automatically bill every temporary provider under another provider’s NPI. The arrangement must meet CMS requirements before the practice uses the Q6 modifier.
CMS source note: Medicare Claims Processing Manual, Publication 100-04, Chapter 1, §30.2.11, Payment Under Fee-For-Time Compensation Arrangements (formerly referred to as Locum Tenens Arrangements).
Medicare Locum Tenens Billing Rules
CMS sets the core locum tenens billing guidelines for Medicare Part B claims in §30.2.11. The main requirements are below.
When Does a Locum Arrangement Qualify?
A regular physician or physical therapist may submit the claim for covered services provided by a substitute when the applicable requirements are met.
For physician arrangements, CMS requires that:
- The regular physician is unavailable to provide the services.
- The Medicare patient has arranged or seeks to receive services from the regular physician.
- 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 for more than 60 continuous days, subject to the applicable exception.
- The services are identified with the Q6 modifier.
For group practices, CMS applies related requirements when the group submits claims in the name of the regular physician. A substitute who has reassigned Medicare payment rights to the group through an approved CMS-855R generally cannot be billed under this fee-for-time arrangement.
CMS also permits certain Medicare-enrolled physical therapists to use substitute physical therapists for outpatient physical therapy services in a health professional shortage area, medically underserved area, or rural area.
How Long Can a Locum Provider Be Billed Under the Arrangement?
The Medicare limit is 60 continuous days.
The count begins with the first day the substitute provides covered visit services to Medicare Part B patients of the regular provider. The period continues even on days when the substitute does not provide services or another substitute covers for the regular provider.
That means a practice should track the arrangement from the first covered date of service rather than counting only the days when the locum actually sees patients.
CMS provides an exception for a physician or physical therapist called to active duty in the Armed Forces.
If coverage needs to continue beyond the applicable 60-day period, the practice should resolve the billing arrangement before continuing to submit claims under the locum framework.
Whose NPI Goes on the Claim?
Under a qualifying Medicare fee-for-time arrangement, the regular physician or physical therapist may submit the claim and receive Part B payment when assignment is accepted.
The Q6 modifier identifies the service as one performed by a substitute. The substitute provider’s NPI must be kept with the record of each service and made available to the Medicare Administrative Contractor upon request.
For medical group claims, CMS also requires identification of the regular physician or physical therapist on whose behalf the services were provided. Practices should follow their current electronic claim format and Medicare Administrative Contractor instructions for the applicable provider identifiers.
The key point is simple: Q6 does not mean the substitute’s NPI replaces the regular provider’s billing identity. It identifies a qualifying substitute arrangement while CMS’s required records document who actually provided the service.
What Records Should a Practice Keep?
The practice should maintain a clear record of each service furnished by the substitute provider and associate that record with the substitute’s NPI.
Operationally, the file should also make it easy to verify:
- The regular provider’s absence
- The substitute provider’s identity
- Dates of coverage
- The compensation arrangement
- Services furnished during the arrangement
- The applicable claim and Q6 reporting
Good documentation gives the billing team a clear audit trail and makes it easier to confirm that each claim met the Medicare requirements. For broader provider paperwork requirements, see our documentation checklist for locum tenens physicians.
What Is the Q6 Modifier and When Do You Use It?
The Q6 modifier identifies a service furnished by a substitute provider under a qualifying Medicare fee-for-time compensation arrangement. It is used with the procedure code on a claim when the regular physician or eligible physical therapist bills for covered services provided by the substitute. Q6 signals that the substitute performed the service while the regular provider remained the billing provider under the applicable rules.
CMS describes Q6 in Chapter 1, §30.2.11 as the modifier for services furnished under a fee-for-time compensation arrangement by a substitute physician or qualifying substitute physical therapist.
How Is Q6 Reported?
For a paper CMS-1500 claim, CMS directs the billing entity to enter Q6 after the procedure code in item 24D.
For electronic claims, billing teams should follow the applicable electronic claim format and payer instructions. CMS’s Physician/Supplier Procedure Summary organizes Medicare Part B claims data by HCPCS code and modifier, providing additional context on how Medicare claims are reported and analyzed.
The modifier should only be used when the underlying arrangement meets the Medicare requirements. Adding Q6 to a claim does not make an otherwise ineligible arrangement compliant.
CMS source: Medicare Claims Processing Manual, Pub. 100-04, Chapter 1, §30.2.11.
Locum Tenens vs. Reciprocal Billing: Q6 vs. Q5
Q6 and Q5 both involve substitute providers, but they describe different Medicare arrangements.
| Modifier | Arrangement | Main distinction |
| Q6 | Fee-for-time compensation | The regular provider pays the substitute on a per diem or similar fee-for-time basis. |
| Q5 | Reciprocal billing | The regular provider arranges occasional reciprocal coverage with another physician. |
CMS addresses reciprocal billing in §30.2.10 and fee-for-time compensation arrangements in §30.2.11.
Do not choose Q5 simply because another physician covered a shift. First determine how the coverage is structured and compensated, then apply the applicable Medicare rule.
How to Bill for Locum Tenens Services: A Worked Example
Consider a family physician who will be unavailable for several weeks. A substitute physician temporarily covers the physician’s Medicare patients and receives payment on a per diem basis.
Step 1: Confirm the Arrangement
The regular physician is unavailable, the patient expects care from that physician, and the substitute is paid on a qualifying fee-for-time basis.
Step 2: Track the Coverage Period.
The billing team records the first date the substitute provides covered Medicare services and monitors the continuous 60-day period.
Step 3: Prepare the Claim.
The regular physician submits the applicable procedure code with the Q6 modifier.
Step 4: Maintain the Substitute’s Information.
The practice keeps a record of the service and the substitute physician’s NPI as required by CMS.
Step 5: Recheck Payer Rules.
If the same service involves Medicaid or a commercial plan, the billing team verifies that payer’s locum policy instead of automatically applying Medicare’s Q6 process. Facilities working with staffing agencies can also review how the agency model affects credentialing, onboarding, contracts, and compliance support.
For example, if the substitute performs an established-patient office visit reported with a CPT code, the claim would include that procedure code followed by Q6 when the Medicare arrangement qualifies. The regular physician remains the provider whose claim is submitted under the fee-for-time framework, while the substitute’s NPI remains in the supporting records.
Medicaid vs. Commercial Payers: What Changes?
Medicare provides a specific federal framework for qualifying locum tenens arrangements. Medicaid and commercial payers may use different rules.
| Payer | What to check |
| Medicare | Apply CMS’s fee-for-time requirements, including the applicable Q6 and 60-day rules. |
| Medicaid | Check the specific state’s Medicaid provider manual and billing policy. |
| Commercial | Review the payer’s contract, provider policy, and credentialing requirements. |
Do not assume that a payer accepts Q6 simply because Medicare does.
Some commercial plans may recognize a similar locum billing process. Others may require the substitute provider to be credentialed or enrolled before the claim is submitted. Medicaid requirements can also differ by state.
For facility billing teams, the safest process is to maintain a payer-specific reference for locum arrangements. Confirm the required modifier, billing NPI, credentialing status, and documentation before the first claim goes out.
Billing for Locum NPs and PAs: What to Check
Do not automatically apply the physician Q6 framework to every NP or PA coverage arrangement.
CMS §30.2.11 expressly addresses substitute physicians and qualifying substitute physical therapists. NP and PA arrangements can involve different Medicare enrollment, billing, supervision, and payer requirements.
Before billing services provided by a locum NP or PA, confirm:
- Who is legally providing the service
- How the practitioner is enrolled with the payer
- Which NPI must appear in the applicable claim fields
- Whether the payer permits the proposed temporary coverage arrangement
- Whether any supervision or incident-to requirements apply
- Whether state licensure requirements are satisfied
Commercial and Medicaid rules should be checked separately because payer requirements can differ from Medicare.
Common Locum Tenens Billing Mistakes
Even when a locum tenens arrangement meets Medicare requirements, billing errors can still cause claim problems. Watch for these common mistakes before submitting claims.
Using Q6 Without a Qualifying Arrangement
Q6 does not automatically apply whenever another provider covers a shift. Confirm the absence, patient relationship, compensation structure, and other Medicare requirements first.
Losing Track of the 60-Day Period
Do not count only days when the substitute sees patients. The continuous period begins with the first covered visit service and continues under CMS’s rules.
Assuming All Payers Follow Medicare
A Medicare-compliant claim can still fail under a commercial payer’s contract or a state Medicaid program. Verify payer-specific requirements before submission.
Failing to Keep the Substitute’s NPI Record
CMS requires a record of each service provided by the substitute along with the substitute’s NPI. Make sure the billing workflow captures this information from the start.
Treating Q5 and Q6 as Interchangeable
Q5 addresses reciprocal billing. Q6 addresses fee-for-time compensation arrangements. Determine which arrangement applies before selecting the modifier.
Locum Tenens Billing Checklist for Facilities
Before submitting claims for a locum provider, confirm:
- The regular provider is unavailable.
- The patient has arranged or seeks services from the regular provider.
- The substitute’s compensation meets the applicable Medicare requirements.
- The arrangement falls within the applicable 60-day period.
- Q6 is used only when the Medicare fee-for-time requirements are met.
- The substitute provider’s NPI is recorded with each applicable service.
- The regular provider or group is identified correctly on the claim.
- Medicaid requirements have been checked separately.
- Commercial payer requirements have been checked separately.
- The billing team has documented the coverage dates and arrangement.
Final Takeaway
Accurate locum tenens billing starts with identifying the type of coverage arrangement before submitting the claim. For qualifying Medicare fee-for-time arrangements, the regular provider can bill for the substitute’s services and use Q6, while the practice maintains the required substitute-provider records.
The 60-day limit, NPI documentation, modifier selection, and payer-specific requirements all need active tracking. Facilities should confirm the applicable Medicare, Medicaid, or commercial rules with their billing team, payer, and compliance staff before submitting claims.
Need help coordinating temporary provider coverage? Imperial Locum supports facilities with locum staffing, credentialing, and related paperwork so your team can focus on maintaining coverage.
Note: This article provides general information, not billing, coding, compliance, or legal advice. Confirm the requirements that apply to your specific arrangement with the relevant payer and your facility’s compliance team.
FAQs
Can a Locum Provider Bill Medicare Under Their Own NPI?
Under a qualifying Medicare fee-for-time arrangement, the regular physician or eligible physical therapist submits the claim. The substitute’s NPI must still be recorded in the required documentation.
What Happens After the 60-Day Limit?
The fee-for-time arrangement generally cannot continue beyond the applicable 60-day limit. If coverage must continue, establish the appropriate billing and enrollment arrangement before submitting more claims.
Is Q6 the Same as Q5?
No. Q6 applies to qualifying fee-for-time compensation arrangements. Q5 applies to Medicare reciprocal billing arrangements under §30.2.10.
Do Commercial Payers Use Q6?
Not necessarily. Commercial payer rules can differ from Medicare requirements. Check the payer’s policy, contract terms, and credentialing requirements before using Q6.
Does Medicaid Follow Medicare’s Locum Tenens Rules?
Not automatically. State Medicaid programs can have their own billing requirements. Check the applicable state Medicaid policy before applying Medicare locum tenens rules.
What Records Should I Keep for Locum Tenens Billing?
Keep the written agreement, coverage dates, reason for the absence, compensation terms, and provider information. Follow applicable payer and facility requirements for record retention.
Can an Excluded Provider Work as a Locum Tenens?
No. An excluded provider cannot provide services billed to Medicare or Medicaid. Screen substitute providers against applicable exclusion and preclusion lists before services begin.
Do Existing Prior Authorizations Apply to Locum Tenens Services?
It depends on the payer. Some payers may honor an existing authorization, while others may require notification or a new authorization for the substitute provider.
Can Nurse Practitioners and PAs Provide Locum Tenens Coverage?
They can provide temporary coverage, but their billing requirements may differ from the physician Q6 framework. Confirm Medicare and payer-specific requirements before submitting claims.
