In this Division –

invalidity , in relation to taxation legislation, includes invalidity of an application of the legislation;

mistake means mistake of law or fact as to the validity or invalidity of any taxation legislation;

public authority means any body corporate established under an enactment or in the exercise of a prerogative right of the Crown to administer or control any department, business, undertaking or public institution on behalf of the State;

tax includes a fee, charge or other statutory impost;

taxation legislation means –

(a) an Act imposing or relating to a tax; or

(b) a provision of that Act; or

(c) a regulation made under that Act; or

(d) a provision of a regulation made under that Act.