B. In the event that the member is unable to pay the purchase price provided for in this section by the due date, the Board shall permit the members to amortize the purchase price over a period not to exceed sixty (60) months. Said payments shall be made by payroll deductions unless the Board permits an alternate payment source. The amortization shall include interest in an amount not to exceed the actuarially assumed interest rate adopted by the Board for investment earnings each year. Any member who ceases to make payment, terminates, retires or dies before completing the payments provided for in this section shall receive prorated service credit for only those payments made, unless the unpaid balance is paid by said member, his or her estate or successor in interest within six (6) months after said member's death, termination of employment or retirement, provided no retirement benefits shall be payable until the unpaid balance is paid, unless said member or beneficiary affirmatively waives the additional six-month period in which to pay the unpaid balance. Notwithstanding anything herein to the contrary, lump-sum payments for a transferred credited service purchase may be made by a cash lump-sum payment; a trustee-to-trustee transfer of non-Roth funds from a Code Section 403(b) annuity or custodial account, an eligible deferred compensation plan described in Code Section 457(b) which is maintained by an eligible employer described in Code Section 457(e)(1)(A), and/or a Code Section 401(a) qualified plan; a direct rollover of tax-deferred funds from a Code Section 403(b) annuity or custodial account, an eligible deferred compensation plan described in Code Section 457(b) which is maintained by an eligible employer described in Code Section 457(e)(1)(A), a Code Section 401(a) qualified plan, and/or a Code Section 408(a) or 408(b) traditional or conduit Individual Retirement Account or Annuity (IRA); or a combination of the foregoing methods. Roth accounts, Coverdell Education Savings Accounts and after-tax contributions shall not be used to purchase transferred credited service. A member making installment payments shall have the option of making a lump-sum payment for the balance of the actuarial purchase price with interest due through the date of payment by a cash lump-sum payment; a trustee-to-trustee transfer of non-Roth funds from a Code Section 403(b) annuity or custodial account, an eligible deferred compensation plan described in Code Section 457(b) which is maintained by an eligible employer described in Code Section 457(e)(1)(A), and/or a Code Section 401(a) qualified plan; a direct rollover of tax-deferred funds from a Code Section 403(b) annuity or custodial account, an eligible deferred compensation plan described in Code Section 457(b) which is maintained by an eligible employer described in Code Section 457(e)(1)(A), a Code Section 401(a) qualified plan, and/or a Code Section 408(a) or 408(b) traditional or conduit Individual Retirement Account or Annuity (IRA); or a combination of the foregoing methods. Roth accounts, Coverdell Education Savings Accounts and after-tax contributions shall not be used to purchase transferred credited service. The Board shall promulgate such rules as are necessary to implement the provisions of this subsection.