Credit card costs continue to spiral upward this year as another major issuer ramps up interest rates. Discover now joins Citibank, Chase, and Providian in raising APRs this year even though the Feds have not dickered with interest rates since December. Discover is notifying cardholders it will raise rates on existing purchase balances to 16.99% and to 22.99% for cash advance balances, effective June 15th. The rate hike does not apply to introductory or promotional rates until they expire. Current Discover cardholders pay interest rates ranging from 12.99% to 14.99% for purchases. Cardholders have until June 8th to reject the new rates. Beginning this month, Chase raised “preferred” credit card interest rates to prime +11.99% with a 19.99% minimum APR. Credit card “non-preferred” interest rates went to a fixed 22.99% interest rate. Providian notified some cardholders in April it was raising rates to 29.99% later this year. Citibank is now charging regular APRs as high as prime +12.99% for standard cards.