25(1)A penalty under paragraph 20 must be paid—
(a)before the end of the period of 30 days beginning with the date on which the notification by HMRC under paragraph 23(1)(b) was issued, or
(b)if a notice of appeal is given, before the end of the period of 30 days beginning with the day on which the appeal is determined or withdrawn.
(2)A penalty under paragraph 20 may be enforced—
(a)where the penalty is payable by a company, as if it were corporation tax charged in an assessment and due and payable;
(b)where the penalty is payable by a partnership, as if it were income tax charged in an assessment and due and payable.