accumulated contribution

(i) all mandatory contributions made by the employee,

(ii) interest (if any) under the plan to the end of the last plan year to which subsection (a)(2) does not apply (by reason of the applicable effective date), and

(iii) interest on the sum of the amounts determined under clauses (i) and (ii) compounded annually—

(I) at the rate of 120 percent of the Federal mid-term rate (as in effect under section 1274 for the 1st month of a plan year) for the period beginning with the 1st plan year to which subsection (a)(2) applies (by reason of the applicable effective date) and ending with the date on which the determination is being made, and

(II) at the interest rate which would be used under the plan under section 417(e)(3) (as of the determination date) for the period beginning with the determination date and ending on the date on which the employee attains normal retirement age.