Section 119
SEC. 119. Additions to the tax in case of non-payment. (a) Tax shown on the return. (1) Payment not extended. — Where the amount of the taxes determined by the donor or the donee as the taxes or any part of such amount is not paid on the due date of the taxes, there shall be collected as a part of the taxes, interest upon such unpaid amount at the rate of one per centum a month from the due date until is paid. (2) Payment extended. — Where an extension of time for payment of the amount so determined as the tax by the donor or the donee has been granted, and the amount the time for the payment of which has been extended, and the interest thereon determined under subsection (a) of section 118 is not paid in full prior to the expiration of the period of the extension, interest at the rate of one per centum a month shall be collected on such unpaid amount from the date when the same was originally due until it is paid. (b) Deficiency. (1) Payment not extended. — Where a deficiency, or any interest assessed in connection therewith, or any addition to the taxes provided for in section 120 is not paid in full within thirty days from the date of the notice and demand from the Collector, there shall be collected as a part of the taxes, interest upon the unpaid amount at the rate of one per centum a month from the date of such notice and demand until it is paid. (2) Payment extended. — If the part of the deficiency the time for payment of which is extended is not paid in accordance with the terms of the extension, there shall be collected, as a part of the taxes, interest on such unpaid amount at the rate of one per centum a month from the date the same was originally due until it is paid. (c) Surcharge. — If any amount of the taxes included in the notice and demand from the Collector of Internal Revenue is not paid in full within thirty days after such notice and demand, there shall be collected in addition to the interest prescribed above and as a part of the taxes a surcharge of five per centum of the unpaid amount.