A Comptroller General making an election under
section 773 of this title who is separated from office before becoming entitled to an annuity under
section 772 of this title is entitled to a lump-sum refund of the amount deducted under
section 773 of this title, plus 4 percent interest before
January 1, 1948, and 3 percent interest after
December 31, 1947, compounded every December 31 until the separation date.