I found this that clears it up:
Age Restrictions - General
With clubs having the full range of age groups from 9s to 16s available in the youth programs, players will
be able to move between grades, up to a maximum of two years, until they turn 15 years old.
A couple of examples are below:
- A player at an NPL or NL1 club turning 11, currently playing for the Premier 11s will be able to
- step up to both the Premier 12s and the NPL / NL1 13s, without seeking an exemption.
- A player at a WPL club currently playing Premier 12s will be able to step up to WPL 13s, but will
- not be able to play WPL15s without seeking an exemption;
- A player 15 years or older can play in any age grade from 15 years and above