(2) (A) In the case of a plan other than a defined benefit plan, the accrued benefit derived from contributions made by an employee as of any applicable date is— (i) except as provided in clause (ii), the balance of the employee’s separate account consisting only of his contributions and the income, expenses, gains, and losses attributable thereto, or (ii) if a separate account is not maintained with respect to an employee’s contributions under such a plan, the amount which bears the same ratio to his total accrued benefit as the total amount of the employee’s contributions (less withdrawals) bears to the sum of such contributions and the contributions made on his behalf by the employer (less withdrawals). (B) Defined benefit plans .— In the case of a defined benefit plan, the accrued benefit derived from contributions made by an employee as of any applicable date is the amount equal to the employee’s accumulated contributions expressed as an annual benefit commencing at normal retirement age, using an interest rate which would be used under the plan under section 1055(g)(3) of this title (as of the determination date). (C) For purposes of this subsection, the term “accumulated contributions” means the total of— (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 section 1053(a)(2) of this title 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 of title 26 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 1055(g)(3) of this title (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. For purposes of this subparagraph, the term “mandatory contributions” means amounts contributed to the plan by the employee which are required as a condition of employment, as a condition of participation in such plan, or as a condition of obtaining benefits under the plan attributable to employer contributions. (D) The Secretary of the Treasury is authorized to adjust by regulation the conversion factor described in subparagraph (B) from time to time as he may deem necessary. No such adjustment shall be effective for a plan year beginning before the expiration of 1 year after such adjustment is determined and published.