(a) Time of payment. The tax imposed by this chapter shall be paid by the donor on or before the 15th day of March following the close of the calendar year.
(b) Extension of time for payment. At the request of the donor, the Director may extend the time for payment of the amount determined as the tax by the donor, for a period not to exceed six months from the date prescribed for the payment of the tax. In such case the amount in respect of which the extension is granted shall be paid on or before the date of expiration of the period of the extension.