Penalty and interest.

(1) In addition to the tax assessed under sub-section (1) of section 117-B or sub-section (2) of section 117-E in the case of submission of incorrect or incomplete return, the Commissioner shall direct the person or employer to pay by way of penalty of one hundred per cent of the difference of the tax assessed and the tax paid as per return: Provided that no penalty under this sub-section shall be imposed after the period of three years from the date of the order of the assessment under this Chapter and unless the person affected has had a reasonable opportunity of showing cause against such imposition. (2) On any amount remaining unpaid after the dates specified for its payment the person or employer shall pay, in addition to the amount due, interest at such rate not exceeding one percent per mensem of such amount for the entire period of default, as may be prescribed.