(a) Ending date. An employee annuity based on disability ends with the earliest of—

(1) The last day of the month before the month in which the employee dies;

(2) The last day of the second month following the month in which the employee's disability ends; or

(3) The last day of the month before the month in which the employee attains full retirement age (the disability annuity is changed to an age annuity).

(b) Effect of ended disability annuity on eligibility for a later annuity. The ending of a disability annuity will not affect an employee's rights to receive any annuity to which he or she later becomes entitled. When a disability annuity ends before an employee attains full retirement age, any additional railroad service the employee has after the disability annuity ends can be credited as if no annuity had previously been paid.