The official FAQ’s under-21 description is a starting point, not a complete age-out analysis for every case.
Ask about the actual dates
Give counsel the child’s birth date and relevant application history, then request an explanation of current applicable rules. Do not assume the first payment freezes age or that expedited processing eliminates the issue. This guide has not verified detailed age-protection mechanics and does not promise that a child will remain eligible through later stages.
Ask what the household should do while the answer is unknown, because that is the question a family actually needs settled. Give counsel the child birth date and the relevant application history and request an explanation of the current applicable rules and of what remains unverified. Then decide which household commitments depend on the child being included and which do not, and keep the first group open.
Do not assume a first payment freezes an age or that expedited handling removes the issue, and do not treat a general description of a limit as an analysis of a particular case. Where the position cannot be established, plan for both outcomes and record the date the question should be revisited. Ask counsel to state plainly which parts of the answer are settled and which are provisional.