5 CFR § 550.804 - Determining entitlement to back pay.
(a) When an appropriate authority has determined that an employee was affected by an unjustified or unwarranted personnel action, the employee shall be entitled to back pay under section 5596 of title 5, United States Code, and this subpart only if the appropriate authority finds that the unjustified or unwarranted personnel action resulted in the withdrawal, reduction, or denial of all or part of the pay, allowances, and differentials otherwise due the employee.
(b) The requirement for a “timely appeal” is met when—
(1) An employee or an employee's personal representative initiates an appeal or grievance under an appeal or grievance system, including appeal or grievance procedures included in a collective bargaining agreement; a claim against the Government of the United States; a discrimination complaint; or an unfair labor practice charge; and
(2) An appropriate authority accepts that appeal, grievance, claim, complaint, or charge as timely filed.
(c) The requirement for an “administrative determination” is met when an appropriate authority determines, in writing, that an employee has been affected by an unjustified or unwarranted personnel action that resulted in the withdrawal, reduction, or denial of all or part of the pay, allowances, and differentials otherwise due the employee.
(d) The requirement for “correction of the personnel action” is met when an appropriate authority, consistent with law, Executive order, rule, regulation, or mandatory personnel policy established by an agency or through a collective bargaining agreement, after a review, corrects or directs the correction of an unjustified or unwarranted personnel action that resulted in the withdrawal, reduction, or denial of all or part of the pay, allowances, and differentials otherwise due the employee.
(e)
(1) The pay, allowances, and differentials paid as back pay under this subpart (including payments made under any grievance or arbitration decision or any settlement agreement) may not exceed that authorized by any applicable law, rule, regulation, or collective bargaining agreement, including any applicable statute of limitations.
(2) An agency may not authorize pay, allowances, and differentials under this subpart in any case for a period beginning more than 6 years before the date of the filing of a timely appeal, or, absent such filing, the date of the administrative determination that the employee is entitled to back pay, consistent with 31 U.S.C. 3702(b). (See also § 178.104 of this chapter.)
(3) For back pay claims dealing with payments under the Fair Labor Standards Act of 1938, as amended (29 U.S.C. 207, et seq.), an agency must apply the 2-year statute of limitations (3 years for willful violations) in 29 U.S.C. 255a. (See also § 551.702 of this chapter.)