In the situation of a locum tenens/substitute provider, can you help me understand the difference between the Q5 and Q6 modifier and when it would be appropriate to use each one?


It's important to understand that these modifiers are not interchangeable. These modifiers recently had their descriptions changed to clarify some of the problems previously associated with them. Use Q5 when there is a reciprocal billing arrangement and use Q6 when there is a fee-for-time compensation arrangement. Medicare has some specific rules about the time involved so be aware of individual payer policies and their time requirements.

Please read the following article for a more detailed explanation of these two modifiers: