Section 120
Section 120 is not paid in full within thirty days from the date of the notice and demand from the Commissioner, there shall be collected as part of the tax, interest upon the unpaid amount at the rate of fourteen per centum per annum, from the date of such notice and demand until it is paid: Provided, That the maximum amount that may be collected as interest on delinquency shall in no case exceed the amount corresponding to a period of three years, the present provisions regarding prescription to the contrary notwithstanding. (2) Payment extended. — If any 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 tax, interest oil such unpaid amount at the rate of fourteen per centum per annum, from the date the same was originally due until it is paid. (c) Surcharge. — If any amount of the tax included in the notice and demand from the Commissioner is not paid in full within thirty days alter such notice and demand, there shall be collected in addition to the interest prescribed above and as part of the tax a surcharge of five per centum of the unpaid amount.