Originally Posted by irishguy28

They won't.

The XPs will be added with an effective date of the date of the flight - i.e. they will count with a date of 31 March and therefore cannot belong to the current, on-going new Platinum year which will already have started at some April date in advance of the OP claiming for these XPs.

I know this the hard way. I refrained from buying SAF for a return ticket for which the outbound was my final flight of one particular membership year, and the inbound flight was the first flight of my subsequent membership year - I had already reached my maximum XP rollover, so didn't need/want the XPs to count for the year in which I took the outbound flight.

I paid for SAF in advance of boarding the inbound flight - my first flight of my new membership year - but the XPs were still associated with the date of the outbound (which I found unfair). Those XPs were then "lost" to me as they counted for the previous, now-ended year, and for which I had already received the maximum allowed rollover (300XP)