Xbox Live Gold 12 month memberships are the most cost-effective use of Microsoft Rewards points (assuming you want Xbox Live Gold), and the "Hot Deal" makes it the best time to redeem!
25% off (12 months for 22,500 points) is even better than the previous two hot deals, which were 20% off (12 months for 24,000 points):
https://www.ozbargain.com.au/node/426087
https://www.ozbargain.com.au/node/385072
12 months is usually 30,000 points, or 29,000 points for level 2 users. (Unfortunately, the 25% discount applies to the full cost of 30,000 points)
1-month and 3-month also discounted (but not as cost-effective use of points).
Ends 15th of May, but the 12 month memberships sell out, so get in asap! (I missed out last time, when they "sold out" less than halfway through the hot deal!)
You can stack up to a maximum of 3 years (36 months) of Xbox Live Gold on your account.
There is also the $1 for 1 month deal still going, which is arguably even more cost effective:
https://www.ozbargain.com.au/node/450332
So your best option may be to claim the $1 deal first, and then add 12 month subscriptions on top of that through Microsoft Rewards. :)
Thanks to Ge3ks on Whirlpool for the heads up! :)
Looks like you can't buy points anywhere. I don't use it enough to earn points. For those looking for cheap subscriptions, CDKeys is legit: https://www.cdkeys.com/xbox-live/memberships/12-month-xbox-l…
This is cheaper but I've not used them before: https://www.g2a.com/en-au/xbox-live-gold-subscription-card-x…