Citi used to allow you to transfer credit line freely between your cards. Around the 2009 timeframe Citi start telling the CSR to tell customers they don't do that anymore and the reason given was the Dodd-frank bill bar them from doing so. The truth is, if you proactively call citi csr and request a credit line transfer, you will get shot down most of the time. However, they will allow you to transfer credit line when you apply for a new citicard and you are not given enough credit for the new card. They even tell you to do that when they ask you to call them to get the card approved.