(a) In the event that a defined benefit plan service award program provides credit for years of ambulance service during the five calendar years immediately preceding the adoption of a program, each ambulance company for which the program is adopted shall identify on the list created pursuant to section 152.7 of this Part participants who are entitled to one or more years of prior service credit and the number of years for which each participant who is entitled to such prior service credit. Any participant who is denied prior service credit for one or more years may appeal to the governing board at the same time, in the same manner, and with like effect as provided in section 152.7 of this Part. Except as otherwise provided in this section, prior service cost shall be paid to the administrator in a single lump sum in the year next following the first calendar year for which a participant earned credit for a year of ambulance service. Such prior service cost shall be calculated by the program actuary.

(b) The governing board of the sponsor may elect to pay initial prior service costs over the five consecutive calendar year period beginning with the calendar year next succeeding the year in which the program takes effect. For this purpose, initial prior service costs means the cost of granting prior service credit to volunteer ambulance workers who become participants as result of having earned a year of ambulance service for activities performed in any year during the five consecutive calendar years beginning with the year in which the program takes effect. Initial prior service costs shall be computed annually during such five-year period and each annual payment shall equal the level annual payment calculated by the program actuary required to amortize the remaining unfunded initial prior service costs over the number of years remaining in such five-year period.

(c) The prior service costs of a service award program for the volunteer ambulance workers of a volunteer ambulance company which contracts with the sponsor of a service award program with one or more other political subdivisions shall be apportioned and paid by such participating political subdivisions in accordance with any agreement between the sponsor and the political subdivision(s); provided, however that unless any such agreement provides otherwise, the portion of the prior service costs of a program allocated to a political subdivision in accordance with such agreement shall be paid in full by a political subdivision even if the political subdivision ceases to contract with the ambulance company after a program is adopted.

(d) In the case of a defined benefit plan service award program converted from a defined contribution plan service award program, the governing board of the sponsor may elect to pay initial prior service costs over the five consecutive calendar year period beginning with the calendar year next succeeding the year in which the conversion takes effect. For purposes of this subdivision, initial prior service costs means the cost of granting prior service credit to volunteer ambulance workers who became or become participants as result of having earned a year of ambulance service for activities performed in any calendar year during the period commencing with the calendar year in which the defined contribution plan program took effect and ending with the fourth calendar year next succeeding the year in which the conversion took effect. Initial prior service costs shall be computed annually during such five-year period and each annual payment shall equal the level annual payment calculated by the program actuary required to amortize the remaining unfunded initial prior service costs over the number of years remaining in such five-year period.

(e) In the case of a defined benefit plan service award program which is amended to provide prior service credit, the governing board of the sponsor may elect to pay initial prior service costs over the five consecutive calendar year period beginning with the calendar year next succeeding the year in which such amendment takes effect. For purposes of this subdivision, initial prior service costs means the cost of granting prior service credit to volunteer ambulance workers who became or become participants as result of having earned a year of ambulance service for activities performed in any calendar year during the period commencing with the calendar year in which the defined benefit plan program took effect and ending with the fourth calendar year next succeeding the year in which the amendment took effect. Initial prior service costs shall be computed annually during such five-year period and each annual payment shall equal the level annual payment calculated by the program actuary required to amortize the remaining unfunded initial prior service costs over the number of years remaining in such five-year period.