There are two ways to retain your tier:
Once you have reached a new tier you have a fixed 12-month period in which to earn the Tier Miles you need to keep your status. During this time, you would need to save 25,000 Tier Miles or take 25 qualifying flights to remain in Silver, 50,000 Tier Miles or 50 qualifying flights to remain in Gold and 150,000 Tier Miles to remain in Platinum.
If you have not managed to stay in your tier after your review date, you will move back to the previous tier. The rolling tier qualification system will resume, meaning we give you a review opportunity every month over the subsequent 12 to 13 months to allow you to regain your status.