The venerable Citi® Double Cash Card – 18 month BT offer — a pioneer in high flat-rate cash-back credit cards — is changing to a points system and eliminating its minimum $25 threshold for redeeming rewards in most cases. According to Citi, starting on March 28, 2022, the card will begin earning rewards as Citi ThankYou points... Funto Omojola writes for NerdWallet.