When I move up a tier, how long do I retain it? For how long will my card be valid?

When you move from Blue to Silver status, or from Silver to Gold, your status review date will be one year from the end of the month in which you achieved your new status.

In other words, you will have until the end of the same month the following year to earn the 25,000 tiers miles (Silver) or 50,000 tier miles (Gold) you require to retain your tier status.

Your membership card and status, and the benefits they afford you, extend two months beyond your review date. This gives you at least 14 months to enjoy your status, and ensures that we can deliver your new card to you before your old one expires. 

For example, if you achieve Silver status on 17th March 2010, your Silver review date will be 31st March 2011. Your Silver status and membership card will therefore be valid until 31st May 2011. If you qualify and renew your Silver status on your review date, your next review date will be set for 31st March 2012, and your new Silver membership card will be valid until 31st May 2012.