s 50M Enforcement
(1) A penalty is to be treated as a debt owed to the Welsh Ministers. (2) The Welsh Ministers may— (a) charge interest on a penalty not paid during the period specified under section 50I(2)(d); (b) impose one or more additional penalties where a penalty is not paid during that period. (3) Interest and additional penalty are to be treated as penalty (and may have the effect of increasing the penalty above a limit set by section 50J). (4) A penalty notice may include provision allowing a discount if the penalty is paid on or before a date specified in the notice (falling within the period specified under section 50I(2)(d)). (5) A person to whom a penalty notice is given on the ground in Case 5 of section 50H may not be prosecuted for the offence by reference to which the penalty notice was given.