20 C.F.R. § 226.90
An employee's annuity may be recomputed to include additional railroad service and compensation and social security wages which the employee earns after the beginning date of the employee annuity. The annuity is recomputed only if the recomputation increases the annuity rate by more than $1 a month or results in a lump-sum payment of more than $5. Before a recomputed rate can be paid, the employee must stop working in the railroad industry. A recomputed tier I component is payable beginning with January 1 of the year after the year in which the wages or compensation are earned or (provided the employee is age 62 or disabled), in the case of railroad compensation, in the year after the employee stops working in the railroad industry. A recomputed tier II component is payable from the date the annuity is reinstated after the employee has ceased railroad work.
20 C.F.R. § 226.90