Originally Posted by CanadaDH

I don't believe the date of the stay needs to be before 31/12 of the following year. Rather, you simply have to make the booking before the SNU expires. In theory, you could use the SNU on the day it expires, against a stay an unlimited period into the future, if the hotel you were booking was accepting reservations for those dates. Every hotel seems to open up their booking windows at completely different times, and I've seen hotels taking bookings greater than a year in advance. The ALL website seems to allow a rolling search period a bit more than 13 months out, but I've also booked reservations beyond that by calling in.

If you earn a SNU in 2021, it will expire 31/12/2022, and you just need to book by 31/12/2022, for any date that is open for booking at the time of booking.

The catch is that you can't cancel the stay after the SNU expires. If you have a SNU that expires 31/12/2022, and book a stay for 2023, and you cancel the stay before before 31/12/2022, the SNU goes back into your account with the original expiry date to use again. If you cancel that same stay after 31/12/2022, the SNU is then lost.