20 CFR §349.2

1. (a)Within 12 months of the date of the notice of such decision, for any reason;
2. (b)Within four years of the date of the notice of such decision:
   1. (1)If there is new and material evidence; or
   2. (2)If the decision was not reasonably consistent with the evidence of record at the time of adjudication.
3. (c)At any time if:
   1. (1)The decision was obtained by fraud or similar fault;
   2. (2)The decision was that the claimant was not a qualified employee, and he or she is now qualified because compensation was credited to the employee's record of compensation in accordance with part 211 of this chapter:
      1. (i)To correct errors apparent on the face of the compensation record;
      2. (ii)To enter items transferred by the Social Security Administration which were credited under the Social Security Act when they should have been credited to the employee's railroad retirement compensation record; or
      3. (iii)To correct errors made in the allocation of earnings to individuals or periods which would have made him or her a qualified employee at the time of the decision if the earnings had been credited to his or her earnings record at that time;
   3. (3)The decision is wholly or partially unfavorable to a claimant, but only to correct a clerical error or an error that appears on the face of the evidence that was considered when the decision was made.