Evasion of payment or the willful refusal on the part of any person to pay taxes, as required by this Subdivision, shall be a misdemeanor and upon conviction the person is subject to imprisonment not exceeding six (6) months or to a fine not exceeding One Thousand Dollars ($1,000), or both, and additionally, to a civil penalty of one hundred percent (100%) of the amount of the assessment, in addition to the actual assessment provided by this Subdivision. Willful refusal is evidenced by failure to pay the full amount due within fifteen (15) days of the date of the assessment.