Hiring locum tenens providers can be a highly effective way to maintain patient access and continuity of care—but without a clear billing strategy, it’s easy to lose revenue or risk compliance issues. From Medicare regulations to private payer policies, navigating locum tenens billing requires a working knowledge of provider classification, documentation standards, and enrollment requirements.

This guide outlines key billing distinctions, best practices, and compliance tips to help healthcare leaders bill accurately and optimize reimbursement when using locum tenens coverage.

First, Know How the Provider Will Be Classified

Billing for locum tenens services starts with determining how the provider will function within your facility: as a replacement physician or a supplemental provider.

Replacement Services

This applies when a locum tenens physician is filling in for a regular, credentialed provider who is temporarily unavailable—for example, due to vacation, illness, or a short leave of absence. Under Medicare guidelines, you may bill for this type of coverage using HCPCS modifier Q6, and services must be provided for no more than 60 continuous days.

Important: The regular physician must be expected to return, and the locum cannot stay beyond 60 days unless under exceptions like military deployment or maternity leave.

Supplemental Services

If the locum tenens provider is augmenting your existing staff—such as supporting growth or covering an unfilled position for more than 60 days—they are classified as a supplemental provider. In this case, the standard provider enrollment process applies, and Q6 cannot be used. This includes completing Medicare Form 855R and securing enrollment with major payers.

Modifier Q6: When and How to Use It

When billing Medicare for services delivered by a replacement locum tenens provider, modifier Q6 should be appended to the procedure code (e.g., on CMS-1500 form, box 24D).

To use Q6 appropriately:

• The regular physician must be unavailable and expected to return
• The locum tenens assignment must not exceed 60 continuous days
• The claim must be billed under the NPI of the absent physician, not the locum

Failure to meet these criteria can result in denied claims or compliance concerns.

Understand Medicare Rules for Each Scenario

Medicare separates locum tenens billing into two categories:

1. Section 30.2.11 – Replacement Physician Services

Allows billing under the absent physician’s NPI with Q6 for up to 60 days.

2. Section 30.2.7 – Supplemental Physician Services

Covers physicians with a contractual agreement to work alongside current staff. These providers must be fully enrolled with Medicare and private payers.

In both cases, the billing entity and the provider share responsibility for overpayments and compliance with claims access.

Private and Medicaid Payor Policies Vary

While many commercial payers and Medicaid programs follow Medicare’s lead, policies differ by state and carrier. Healthcare leaders should:

• Identify their top three to five payers by volume
• Confirm whether Q6 is accepted for replacement coverage
• Determine provider enrollment requirements for supplemental roles
• Track the payer mix (Medicare, Medicaid, commercial) across service lines

Aligning billing practices with each payer’s expectations ensures claims are accepted and cash flow is protected.

Best Practices for Locum Tenens Billing Compliance

To avoid delays, denials, or audits, ensure the following processes are in place:

1. Accurate Documentation

Maintain clear records of the locum’s start and end dates, coverage duration, services performed, and any contractual agreements.

2. Internal Tracking

Flag the locum’s coverage period in your scheduling and billing systems. Assign reminders to monitor the 60-day limit if Q6 is used.

3. Credentialing & Enrollment Support

Partner with your locum tenens staffing agency to expedite credentialing and licensing. For supplemental roles, begin enrollment with major payers as early as possible.

4. Clean Claims Submission

Double-check CPT codes, modifiers, NPIs, and dates of service before submitting claims. Mismatches in documentation and billing are a top cause of delays.

5. Regular Claims Review

Analyze locum-related claims separately within your revenue cycle reports. Look for recurring issues tied to documentation, denial trends, or payer-specific errors.

Common Billing Mistakes to Avoid

• Using Q6 for assignments over 60 days
• Submitting claims under the locum’s NPI for replacement services
• Failing to begin payer enrollment early for supplemental providers
• Incorrectly coding the type of coverage provided
• Missing documentation for contract terms or service logs

A small oversight in classification or modifier use can delay payments or trigger recoupments during audits.

Optimize Revenue with Strategic Locum Billing

Locum tenens staffing isn’t just about coverage—it’s about protecting patient access and preserving revenue. By properly classifying providers, aligning with payer requirements, and following Medicare rules, your organization can ensure timely reimbursement and minimize risk.

Need support managing locum tenens billing or coverage planning? Partner with Caliber for strategic staffing solutions built on compliance, flexibility, and operational performance.