20 C.F.R. § 10.501

(a) The employee is responsible for providing sufficient medical evidence to justify payment of any compensation sought.

(1) To support payment of continuing compensation where an employee has been found entitled to periodic benefits, narrative medical evidence must be submitted whenever OWCP requests it but ordinarily not less than once a year and with any filing of a form CA-1032. It must contain a physician's rationalized opinion as to whether the specific period of alleged disability is causally related to the employee's accepted injury or illness.

(2) For those employees with more serious conditions not likely to improve and for employees over the age of 65, OWCP may require less frequent documentation, but ordinarily not less than once every three years.

(3) The physician's opinion must be based on the facts of the case and the complete medical background of the employee, must be one of reasonable medical certainty and must include objective findings in support of its conclusions. Subjective complaints of pain are not sufficient, in and of themselves, to support payment of continuing compensation. Likewise, medical limitations based solely on the fear of a possible future injury are also not sufficient to support payment of continuing compensation. See § 10.330 for a fuller discussion of medical evidence.

(b) OWCP may require any kind of non-invasive testing to determine the employee's functional capacity. Failure to undergo such testing will result in a suspension of benefits. In addition, OWCP may direct the employee to undergo a second opinion or referee examination in any case it deems appropriate (see §§ 10.320 and 10.321).