(a) A DRC is due for each month after 1970 in which the employee is—

(1) Full retirement age or older and under age 70 (72 before 1984); and

(2) Fully insured under section 214(a) of the Social Security Act based on combined railroad and social security earnings; and either—

(i) Is not entitled to an annuity because he or she did not apply for an annuity; or

(ii) Is entitled to an annuity but has the full amount of the tier I and vested dual benefit work deduction component (described in part 226 of this chapter) or the social security overall minimum rate (described in part 229 of this chapter) withheld because of earnings in excess of the exempt amount (as explained in part 230 of this chapter).

(b) The months for which credit is due need not be consecutive.