Modifier Q6
A practical medical billing guide to Modifier Q6: what it means, when it can be reported, the 60-day rule, substitute physician requirements, claim billing, documentation, denial management and AR follow-up.
Modifier Q6 at a Glance
The essential facts every medical biller should know.
Substitute Physician
Q6 identifies eligible services furnished by a substitute physician under a qualifying locum tenens arrangement.
60-Day Rule
Generally, the substitute physician cannot provide the services over a continuous period longer than 60 days.
Fee-for-Time
The arrangement involves per-diem or similar fee-for-time compensation.
Medicare
Medicare has specific claims-processing requirements for fee-for-time compensation arrangements.
What Is Modifier Q6?
Understand the concept before applying the modifier.
Simple Definition
Modifier Q6 indicates that a service was furnished by a locum tenens substitute physician under Medicare’s fee-for-time compensation rules.
In a qualifying arrangement, the regular physician or practice bills Medicare for the covered service as though the regular physician furnished it, while the substitute physician provides the actual patient care.
Q6 = eligible substitute physician / locum tenens service.
Q6 Is More Than a Modifier
Reporting Q6 is not simply a matter of adding a modifier because another physician performed the service.
The underlying arrangement must satisfy Medicare’s requirements for fee-for-time compensation.
The biller should therefore verify the reason for the substitution, compensation arrangement, duration of the substitution and claim identification requirements.
If the arrangement does not meet Medicare’s requirements, adding Q6 does not make the service a valid locum tenens claim.
Why Are Locum Tenens Physicians Used?
Common situations that can create a temporary physician substitution.
Illness
A regular physician may temporarily be unable to provide patient services because of illness.
Pregnancy
A physician may arrange temporary coverage during an absence related to pregnancy or maternity.
Vacation
Temporary physician coverage can help maintain continuity of patient care during planned absences.
CME
A substitute may cover the regular physician’s patients while the physician attends continuing medical education.
Temporary Coverage
Practices may use substitute physicians when temporary clinical coverage is necessary.
Practice Continuity
The goal is to maintain patient access while the regular physician is unavailable.
Medicare Q6 Requirements
These conditions should be reviewed before billing.
Regular Physician Is Unavailable
The regular physician must be unavailable to provide the visit or professional service.
Patient Relationship
The Medicare beneficiary has arranged or seeks to receive the service from the regular physician.
Fee-for-Time Compensation
The regular physician pays the substitute physician on a per-diem or similar fee-for-time basis.
Continuous Period
The substitute physician generally cannot provide the services over a continuous period longer than 60 days.
Correct Claim Identification
The claim must identify the service as being furnished under the applicable substitute physician arrangement.
Record Retention
The billing practice should maintain records identifying services furnished by the substitute physician.
The 60-Day Rule
One of the most important Q6 billing requirements.
Generally No More Than 60 Days
Medicare’s fee-for-time compensation policy generally permits the substitute physician to furnish services for a continuous period of no more than 60 days.
The limitation is based on the continuous period of substitute services, so billing teams should track the coverage dates carefully.
A separate exception applies when the regular physician has been called or ordered to active duty as a member of a reserve component of the Armed Forces.
AR Warning
Do not assume that every temporary physician arrangement automatically qualifies for Q6.
If the coverage extends beyond the applicable period, investigate whether the arrangement remains eligible or whether another billing arrangement applies.
Document the actual start and end dates rather than relying on memory or informal scheduling notes.
Q6 Billing Workflow
From temporary coverage arrangement to claim submission.
Q6 vs Other Physician Arrangements
Do not confuse locum tenens billing with other situations.
| Situation | Basic Concept | Q6? | Billing Focus |
|---|---|---|---|
| Locum Tenens | Substitute physician provides services under a qualifying fee-for-time arrangement. | Yes, when requirements are met. | Q6 and applicable substitute physician requirements. |
| Permanent Replacement | Another physician permanently takes over the practice or patient care. | Not automatically. | Verify enrollment and ordinary billing rules. |
| Group Physician Coverage | Another physician in the group provides services as part of normal practice operations. | Not simply because another group physician treated the patient. | Apply applicable group practice billing rules. |
| Employee Physician | Physician provides services as an employee of the practice. | Not automatically. | Follow employment and billing requirements. |
| Independent Contractor | Contractual relationship that may or may not satisfy fee-for-time locum tenens requirements. | Depends on the arrangement. | Verify all Medicare requirements. |
Where Is Q6 Reported?
Understand the professional claim workflow.
CMS-1500 / Professional Claim
Q6 is reported as a modifier with the applicable procedure code on the professional claim.
Procedure Code + Q6
The actual CPT/HCPCS code depends on the service furnished.
Provider Identification
The billing arrangement must correctly identify the regular physician or medical group and comply with applicable Medicare claim-identification requirements.
Practices should maintain records identifying the substitute physician and the services furnished.
Modifier Q6 Practical Examples
Real-world billing scenarios for RCM teams.
Dr. Smith is unavailable because of vacation. A substitute physician temporarily sees Dr. Smith’s Medicare patients.
If all Medicare fee-for-time requirements are satisfied, the applicable services may be reported with Q6.
A physician attends a continuing medical education program and arranges for a substitute physician to see scheduled patients.
Verify the fee-for-time arrangement and all other Medicare requirements before billing.
A practice schedules a substitute physician for a continuous period extending beyond 60 days.
Do not automatically continue reporting Q6. Review the duration and applicable exception or billing rule.
A physician permanently leaves a medical group and the group temporarily hires another physician to cover the departing physician’s patients.
CMS recognizes circumstances involving a physician who has left a group and temporary locum coverage, subject to the applicable requirements.
Dr. Jones, who is already a physician in the same group, sees a patient because Dr. Smith is busy that afternoon.
Another physician performing the service does not by itself establish a qualifying locum tenens arrangement.
A substitute physician is paid under an arrangement that does not meet the applicable fee-for-time requirements.
Verify the contractual and payment arrangement before reporting Q6.
Q6 Documentation Checklist
Maintain evidence that supports the locum tenens arrangement.
Practice Documentation
- Regular physician’s name and NPI.
- Substitute physician’s name and NPI.
- Reason for the physician’s absence.
- Start and end dates of substitution.
- Fee-for-time compensation arrangement.
- Patient/service records.
- Internal coverage schedule.
Billing Documentation
- Correct CPT/HCPCS code.
- Q6 reported when applicable.
- Correct billing provider information.
- Substitute physician information retained.
- Date-of-service verification.
- Medicare eligibility and coverage verified.
- Payer-specific rules reviewed.
Q6 Denial Management for AR Callers
Identify the root cause before submitting a correction.
Read the ERA
Identify the exact denial reason and review the CARC/RARC information associated with the claim line.
Verify Q6
Confirm whether Q6 was present and whether the underlying arrangement actually qualifies.
Verify Dates
Compare the substitute physician’s coverage dates against the applicable continuous-period requirement.
Check Provider Data
Verify the billing provider, regular physician and substitute physician information.
Review Records
Confirm the practice maintains documentation supporting the locum tenens arrangement.
Correct or Appeal
Correct the claim when appropriate or submit a reconsideration/appeal supported by documentation.
Common Modifier Q6 Denial Causes
These are the areas an AR caller should investigate first.
Q6 Missing
The claim may have been submitted without the required locum tenens modifier.
Q6 Incorrect
Q6 was added even though the underlying arrangement did not satisfy the applicable requirements.
Duration Issue
The substitute physician’s continuous coverage period exceeded the applicable limit.
Provider Mismatch
Provider identifiers or billing information do not match the Medicare claim requirements.
Documentation Missing
The practice cannot provide records identifying the substitute physician and services.
Enrollment Issue
The claim may involve provider enrollment or identification issues that need separate investigation.
Wrong CPT/HCPCS
The procedure code itself may not match the service documented.
Payer Edit
A Medicare contractor or other payer may have applied a claim-specific processing edit.
Wrong Billing Arrangement
The actual contractual relationship may not qualify as Medicare fee-for-time locum tenens.
AR Caller Script for a Q6 Denial
Practical questions to ask the Medicare representative.
How to Correct a Q6 Denial
Use the root cause to determine the next action.
How to Prevent Q6 Denials
Build locum tenens validation into the RCM workflow.
Front-End / Practice Team
- Document the regular physician’s absence.
- Record the substitute physician’s information.
- Maintain the coverage start and end dates.
- Document the compensation arrangement.
- Track the continuous substitution period.
- Communicate coverage changes to billing.
Billing / RCM Team
- Validate Q6 before claim submission.
- Verify the CPT/HCPCS code.
- Confirm provider identifiers.
- Check substitution dates.
- Monitor the 60-day limitation.
- Maintain a Q6 denial trend report.
Modifier Q6 Audit Matrix
Use this checklist before releasing a locum tenens claim.
| Audit Question | YES | NO | Action |
|---|---|---|---|
| Is the regular physician unavailable? | Continue | Review arrangement | Confirm reason for substitution |
| Is the substitute physician actually providing the service? | Continue | Stop | Verify service provider |
| Is the arrangement fee-for-time? | Continue | Investigate | Verify compensation arrangement |
| Is the substitution within the applicable continuous period? | Continue | Investigate | Review 60-day rule / applicable exception |
| Is Q6 appropriate? | Add Q6 | Do not add | Follow Medicare billing rules |
| Are provider identifiers correct? | Continue | Correct | Validate NPI/provider data |
| Is documentation available? | Continue | Hold | Obtain supporting records |
| Is the payer’s policy satisfied? | Submit | Verify | Follow applicable payer instructions |
Modifier Q6 Quick Cheat Sheet
Save this section for daily AR and billing reference.
- Q6 identifies eligible services furnished by a substitute physician under a fee-for-time compensation arrangement.
- The regular physician must be unavailable to provide the service.
- The patient relationship is generally with the regular physician.
- The regular physician pays the substitute physician on a per-diem or similar fee-for-time basis.
- The substitute physician generally cannot provide services over a continuous period longer than 60 days.
- There is a special active-duty exception for certain reserve component members of the Armed Forces.
- Q6 should not be added merely because another physician treated the patient.
- Maintain documentation identifying the substitute physician and services provided.
- Verify provider identification and claim information.
- Review the actual arrangement before correcting a denied claim.
- Medicare Advantage and commercial payer rules should be verified separately.
Modifier Q6 FAQs
Common questions from medical billers, coders and AR callers.
What does Modifier Q6 mean?
Modifier Q6 identifies an eligible service furnished by a substitute physician under Medicare’s fee-for-time compensation arrangement rules.
What is a locum tenens physician?
A locum tenens physician is a substitute physician who temporarily provides services for a regular physician who is unavailable, when the arrangement meets the applicable requirements.
What is the Q6 60-day rule?
Medicare generally limits the substitute physician’s services to a continuous period of no more than 60 days under the fee-for-time compensation policy.
Is there an exception to the 60-day rule?
Yes. CMS provides an exception when the regular physician has been called or ordered to active duty as a member of a reserve component of the Armed Forces.
Can I use Q6 whenever another physician sees the patient?
No. The fact that another physician provided the service does not by itself establish a qualifying locum tenens arrangement.
Does Q6 mean the substitute physician bills Medicare directly?
Under the qualifying arrangement, Medicare payment is generally made to the regular physician or applicable medical group under its billing number, rather than the substitute physician billing as though the service were his or her ordinary independent practice.
How is Q6 reported on a claim?
Q6 is reported with the applicable CPT or HCPCS procedure code on the professional claim when the service meets the applicable locum tenens requirements.
What documentation should the practice keep?
The practice should maintain records supporting the substitution, including the regular physician, substitute physician, services provided and relevant arrangement details.
Can a medical group use Q6?
CMS provides specific rules for medical groups using substitute physicians. The applicable requirements must be satisfied before reporting Q6.
Does Q6 apply to every payer?
No. This page primarily explains Medicare rules. Medicare Advantage, Medicaid and commercial insurers can have additional or different requirements.
What should an AR caller check when Q6 is denied?
Check the denial code, Q6 modifier, CPT/HCPCS code, substitute physician, regular physician, provider identifiers, substitution dates, compensation arrangement and whether the continuous-period requirement was met.
Can Q6 be corrected after a denial?
If the claim was incorrectly submitted and the underlying service qualifies, a corrected claim may be appropriate when the payer permits correction. Always verify the payer’s correction and appeal instructions.
Is Q6 the same as a permanent physician replacement?
No. Locum tenens represents temporary substitute coverage. A permanent replacement should be evaluated under the applicable enrollment and ordinary billing rules.
Is Q6 the same as Modifier Q5?
No. Q6 is associated with fee-for-time compensation arrangements involving substitute physicians. Q5 is used for reciprocal billing arrangements. The two concepts should not be confused.
Official CMS References
Primary sources for Medicare Q6 verification.
Educational Disclaimer
This page is for US medical billing, coding and Revenue Cycle Management education. Medicare rules can change, and Medicare Advantage, Medicaid and commercial payers may apply different requirements. Always verify the applicable policy, payer instructions and date-of-service requirements before submitting or appealing a claim.
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