Parliamentary scrutiny requirement: tax rules and notifications must be laid before Parliament and may be modified or annulled after review. Rules and notifications under the Inland Air Travel Tax must be laid before each House of Parliament while in session for a cumulative thirty days, which may span one or more sessions; if, before the expiry of the following session, both Houses agree to modify or annul the instrument, it shall thereafter operate only in the modified form or be of no effect, but such modification or annulment does not affect the validity of actions previously taken under the rule or notification.