At the end of every year, the tier credit balance is reset to zero. The status you have in the following year will be determined by how many credits you have at the end of the year.

- If you had earned Platinum, then you hold that from the time you reach the tier points until the end of that qualifying year. For a lot (if not most) they reach their level before the end of the year so they generally have > 12 months at that level.
- If you didn't have enough for Platinum, but enough for Silver, then Silver it will be for the following year.

The following year you'll need to earn the points for any level again.