Section 3(f)(3) of the Railroad Retirement Act, the social security overall minimum provision, guarantees that an annuitant will receive, in combined benefits under the Railroad Retirement and Social Security Acts, not less than the amount which would have been paid to the employee and to members of his or her family under the Social Security Act if the employee's railroad service had been creditable under that Act. An annuitant whose annuity is computed under that provision may assign all or any portion of that annuity to any of the members of his or her family who are or who could be included in the computation of the annuity. Any assignment issued pursuant to this section will terminate:

(a) When revoked by the annuitant by notification to the Board; or

(b) When the annuity is no longer computed under the social security overall minimum provision.