17(1)A penalty under paragraph 14 must be paid—
(a)before the end of the period of 30 days beginning with the day on which the notification under paragraph 15 was given, or
(b)if notice of an appeal against the penalty is given, before the end of the period of 30 days beginning with the day on which the appeal is finally determined or withdrawn.
(2)A penalty under paragraph 14 may be enforced as if it were income tax charged in an assessment and due and payable.