Have a Discover it card but haven’t gotten around to signing up for the Double Cash Back promotion? Unfortunately, it appears that Discover has silently ended the enrollment period for existing cardmembers. As of today, the promotion, which doubles all of the cash back that you earn with the card for one year–including cash back earned on 5% category spend and Discover Deals–is now available to new cardholders only.

Since you can have two different Discover accounts–provided you have had the first account for at least a year–if you already have one Discover it card, it is possible to apply for a new card with the promotion on it, but it no longer appears to be possible to add the promotion to an existing card. It’s a shame for those who missed out, especially for those who were looking to double dip on Discover it’s 5% categories next quarter, which include home improvement stores, department stores and Amazon.com.