[17Decisions superseding earlier decisionsE+W+S
(1)Subject to subsection (2), the following, namely—
(a)any decision of the [Commission] under section 11 or 12 or this section, whether as originally made or as revised under section 16;
(b)any decision of [the First-tier Tribunal] under section 20; ...
(c). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
[(d)any decision of [the First-tier Tribunal] on a referral under section 28D(1)(b);
(e)any decision of [the Upper Tribunal] on an appeal from such a decision as is mentioned in paragraph (b) or (d)],
may be superseded by a decision made by the [Commission], either on an application made for the purpose or on [its] own initiative.
(2)In making a decision under subsection (1), the [Commission] need not consider any issue that is not raised by the application or, as the case may be, did not cause [it] to act on [its] own initiative.
(3)Regulations may prescribe the cases and circumstances in which, and the procedure by which, a decision may be made under this section.
[(4)Subject to subsection (5) and section 28ZC, a decision under this section shall take effect as from the beginning of the maintenance period in which it is made or, where applicable, the beginning of the maintenance period in which the application was made.
(4A)In subsection (4), a “maintenance period” is (except where a different meaning is prescribed for prescribed cases) a period of seven days, the first one beginning on the effective date of the first decision made by the [Commission] under section 11 or (if earlier) [its] first default or interim maintenance decision (under section 12) in relation to the non-resident parent in question, and each subsequent one beginning on the day after the last day of the previous one.]
(5)Regulations may provide that, in prescribed cases or circumstances, a decision under this section shall take effect as from such other date as may be prescribed.]