40 Pa. Stat. § 611
Every person subscribing to the guarantee capital of any mutual life insurance company, organized under this act, shall give to said company his note or obligation, in such form as the by-laws of the company may prescribe, for the unpaid moiety of the guarantee capital so subscribed, which note or obligation shall be liable to assessment or assessments, from time to time, as may be deemed necessary by the directors or trustees of said company for the successful prosecution of its business. Such assessments may be made to meet the losses, expenses, insurance reserve, and other obligations of such company, until the whole amount of such note or obligation shall be paid. All assessments shall be made pro rata upon the entire amount of unpaid subscriptions, and, if such assessments are not paid, the same shall be collected by suit at law as other debts of like character are collectible.
40 P.S. § 611