20 CFR 225.52 - Reasons for recomputing a PIA.
There are three major reasons for recomputing a PIA:
(a) Recomputation to consider additional earnings.
(b) Recomputation when an employee is eligible for periodic pension payments based on other than railroad or social security earnings.
(c) Recomputation to use a new or different PIA formula, as provided in section 215(f) of the Social Security Act.