To upgrade to a higher Tier, you need to accrue InterMiles against Qualifying Activities in a rolling 12 months period as per the requirements of the next higher Tier. Every day, our Dynamic Tier Review system reviews the InterMiles earned by you in the preceding 12 months and as soon as you accrue the required InterMiles, the Tier status is immediately upgraded to the next higher level. For more information on the Dynamic Tier Review and Tier retention/upgrade, please visit Dynamic Tier Review