All persons appointed to an office by the governor, or elected under the provisions of any law of this commonwealth, the gross receipts of whose office shall exceed six hundred dollars and not exceed twelve hundred dollars, shall pay into the treasury of the state, a tax of one per centum, and on all amounts over twelve hundred dollars and not exceeding twenty-five hundred dollars, two per centum, and on all amounts exceeding twenty-five hundred dollars, five per centum annually.
72 P.S. § 3192