When and how to use Q6 and Q5 modifiers

Can I use a locums modifier during credentialing?

A new provider waiting for credentialing or enrollment does not qualify for Q5 or Q6 simply because the process is taking time. The arrangement must meet the payer’s substitute-provider requirements.

We understand the frustration of waiting for payer approval, but a paid claim does not establish that the billing was appropriate. Do not treat substitute billing or incident-to billing as a general workaround. Each has its own requirements.

For commercial plans, confirm the payer’s written policy and any case-specific authorization before submitting claims. Ask whether an out-of-network authorization is available when appropriate. Medicare’s Q5 and Q6 rules do allow qualifying substitute arrangements; they should not be confused with permission to bill for any new hire awaiting enrollment.

1. When is substitute coverage appropriate?

A substitute physician may cover for a regular physician who is unavailable because of illness, vacation, continuing education, pregnancy or another absence. The Medicare patient must have arranged or sought services from the regular physician, and the other requirements must be met.

Medicare also permits a qualifying temporary replacement for a physician who has left a group, subject to the time limit and group-billing rules. Hiring a new provider who is not yet enrolled, by itself, is not a qualifying reason.

2. How long can substitute billing continue?

The general Medicare limit is 60 continuous days. The period begins on the first day the substitute provides covered services to the regular physician’s Medicare patients. It includes days with no visits and days covered by a different substitute. Changing substitutes does not restart the clock.

If coverage will continue beyond the permitted period, arrange the necessary enrollment and billing under the substitute’s own identity. Review any applicable exception with your Medicare Administrative Contractor (MAC).

3. Can a substitute physician perform surgery?

Yes, when the physician is appropriately qualified and the service and billing arrangement meet the applicable requirements. When the substitute provides only postoperative care already included in a global surgical fee, Medicare does not require that care to be identified separately as substitute services on the claim.

4. How do I submit the claim?

For a qualifying fee-for-time arrangement, append Q6 after the procedure code in item 24D of the CMS-1500 or the corresponding electronic claim field. Use the regular physician’s NPI in the rendering-provider field under the substitute-billing instructions. Qualifying reciprocal arrangements use Q5.

Confirm the claim setup with your billing team and MAC. Group claims and hospice attending-physician coverage have specific rules; do not assume ordinary coverage by another enrolled group member requires Q5.

5. What records should I keep?

Keep the clinical record for each service, the date of service and the substitute physician’s NPI. Maintain a coverage log that allows your team to track the continuous period and identify who actually provided each service. Medicare can request these records.

6. How should I pay the substitute?

For Q6, the regular physician or group pays the substitute on a per diem or similar fee-for-time basis, such as an hourly arrangement. Review the compensation and employment arrangement against the fee-for-time requirements. A productivity-based payment arrangement should not be treated as equivalent simply because the work is temporary.

7. Is there an exception to the 60-day limit?

Medicare allows coverage beyond the usual limit when the regular physician or qualifying physical therapist is called to active duty in the Armed Forces. Confirm the documentation and claim requirements with your MAC before applying the exception.

8. When should I use Q5 for reciprocal billing?

Q5 identifies services furnished under a qualifying reciprocal coverage arrangement. It is different from the fee-for-time arrangement identified by Q6.

Q5 is not limited to physicians sharing the same tax ID. The earlier version of this article incorrectly described it that way. For group claims, Medicare generally requires identification of the group member who actually performed the service. The CMS manual explains the requirements for substitutes who have not reassigned benefits to the group, along with the specific hospice attending-physician exception.

Use CMS Claims Processing Manual, chapter 1, sections 30.2.10 and 30.2.11, to evaluate the actual arrangement with your billing team.

Outpatient physical therapy: Q5 and Q6

Medicare’s substitute-billing provisions also apply to certain outpatient physical therapy services furnished in a health professional shortage area, a medically underserved area or a rural area. The geographic and coverage requirements matter; these modifiers are not a general substitute-billing option for every therapy practice.

Q6 identifies an eligible fee-for-time arrangement, while Q5 identifies an eligible reciprocal arrangement. Review the location, duration and documentation requirements before billing.

• Noridian: outpatient physical therapy substitute billing
• Therapy Practice Services: using Q6 for outpatient physical therapy
• CMS change request 10090 (PDF)