16 Pa. Stat. § 7372
He shall cause to be kept a full and regular set of books, in detail, by double entry, of all the fiscal operations of the county, embracing as many accounts under appropriate titles as may be necessary to show distinctly and separately all the property of the county, its receipts and expenditures, and all debts and accounts due by the county officers or others the amount raised from each source of revenue, and the expenditures in detail, and classified by reference to the objects thereof; he shall prescribe the form and manner of keeping the books and papers used by each of the officers of said county in connection with the fiscal affairs of the county, and he shall, on or before the first day of February, annually, communicate to the commissioners, in writing, a detailed estimate of and for the legitimate purposes of the county for the current year, including interests due and to fall due on all lawful debts of the county bearing interest, and the commissioners shall, on or before the fifteenth day of February thereafter, fix such rate of taxation upon the valuation of the property of the county as will raise sufficient sum to meet the said expenditures, and the commissioners shall not, by contract or otherwise, increase the expenditures of the county in any year to an amount beyond the taxes assessed as aforesaid for said year.
16 P.S. § 7372