77 Pa. Stat. § 393
All unallocated liability loss expense payments made in a given calendar year subsequent to the first four years in which an insurer has been issuing liability policies, shall be distributed as follows: Thirty-five per centum shall be charged to the policies written in that year; forty per centum to the policies written in the preceding year; ten per centum to the policies written in the second year preceding; ten per centum to the policies written in the third year preceding; and five per centum to the policies written in the fourth year preceding. And such payments, made in each of the first four calendar years in which an insurer issues liability policies, shall be distributed as follows: In the first calendar year, one hundred per centum shall be charged to the policies written in that year; in the second calendar year, fifty per centum shall be charged to the policies written in that year, and fifty per centum to the policies written in the preceding year; in the third calendar year, forty per centum shall be charged to the policies written in that year, forty per centum to the policies written in the preceding year, and twenty per centum to the policies written in the second year preceding; and in the fourth calendar year, thirty-five per centum shall be charged to the policies written in that year, forty per centum to the policies written in the preceding year, fifteen per centum to the policies written in the second year preceding, and ten per centum to the policies written in the third year preceding; and a schedule showing such distribution shall be included in the annual statement.
All unallocated compensation loss expense payments made in a given calendar year subsequent to the first three years in which an insurer has been issuing compensation policies, shall be distributed as follows: Forty per centum shall be charged to policies written in that year; forty-five per centum to the policies written in the preceding year; ten per centum to the policies written in the second year preceding; and five per centum to the policies written in the third year preceding. And such payments made in each of the first three calendar years in which an insurer issues compensation policies, shall be distributed as follows: In the first calendar year, one hundred per centum shall be charged to the policies written in that year; in the second calendar year, fifty per centum shall be charged to the policies written in that year, and fifty per centum to the policies written in the preceding year; in the third calendar year, forty-five per centum shall be charged to the policies written in that year, forty-five per centum to the policies written in the preceding year, and ten per centum to the policies written in the second year preceding; and a schedule showing such distribution shall be included in the annual statement.
77 P.S. § 393