40 Pa. Stat. § 791
Any subscriber of any employers' mutual liability insurance association who has complied with all of its rules and regulations may withdraw therefrom by written notice to that effect, sent by such subscriber by registered mail to the association. Such withdrawal shall become effective on the first day of the month immediately following the tenth day after the receipt of such notice. Such withdrawal shall not release such subscriber from liability for the payment of assessments thereafter made by the board of directors to make up deficiencies existing at the date of his withdrawal, provided assessment therefor is made within one calendar year from date of withdrawal; and such subscriber shall be entitled to his share of any dividend earned at the date of his withdrawal.
40 P.S. § 791