Final answer:
A written agreement is not required under Stark regulations in certain situations, such as when the compensation arrangement does not exceed fair market value or when it falls within the exceptions outlined in the regulations.
Step-by-step explanation:
In certain situations, a written agreement is not required under Stark regulations. One such situation is when the compensation arrangement between a physician and a hospital or entity does not exceed fair market value for the services provided.
Another situation is when the arrangement falls within one of the exceptions outlined in the Stark regulations, such as the rental of office space or equipment at fair market value. Additionally, if the arrangement is with an immediate family member of the physician, a written agreement may not be required.