I think AC needs to spell it out in their T&C (like quite literally every other loyalty program) on when published benefits expire if they are unused/unselected/etc.

"Benefit year" - great. Spell out how the benefit year is defined.

Because nothing feels worse than losing out on benefits you're entitled to, because one year AC decided cut off for benefits selection was Dec 30th instead of Dec 31st, etc. Or in my case, losing out on them because I qualified on Dec 28th, but AC took until Jan 1 to count my SQM/SQD.