Section 30. That in the settlement by the Auditor General and State Treasurer of all accounts for taxes due the Commonwealth, they shall charge interest upon the amount of tax or balance or balances found due the Commonwealth, at the rate of twelve per centum per annum from thirty days after the time said taxes or balances become due and payable to the time of the settlement of the same; and all balances due the Commonwealth on accounts settled by the Auditor General and State Treasurer shall bear interest from sixty days after date of settlement at the rate of twelve per centum per annum until the same are paid, except where appeals have been taken from settlements made by the Auditor General or by the Auditor General and State Treasurer; and any judgments recovered thereon, except where appeals have been taken as aforesaid, shall bear interest at the rate of twelve per centum per annum until paid; and the payment of interest as aforesaid shall not relieve any corporation from any of the penalties or commissions prescribed by law for neglect or refusal to furnish reports to the Auditor General or to pay any claim due to the Commonwealth from such corporation: Provided, That the Auditor General shall first have sent to such corporation a statement of the amount due.