Every association shall be subject to, and shall pay for, the privilege of doing business in this Commonwealth, or having capital or property employed or used in the Commonwealth, by, or in the name of itself, or any other person, partnership or association, a State excise tax at the rate of four per centum (4%) per annum upon each dollar of the net income, which tax shall be collected in lieu of any other excise tax except liquid fuel taxes, fuel use taxes, sales and use taxes on registered motor vehicles and unemployment compensation fund contributions but including corporate net income tax or property tax. Nothing contained herein shall be construed to impose an excise tax upon any subject of taxation when such subject of taxation is specifically exempted under the statute levying the excise tax. The property shall be free from any county tax excepting tax on real estate.