Oklahoma Credit unions’ federal tax exemption no longer serves its purpose as the industry moves even further away from its mission of providing consumer-focused financial services to people of modest means. One Oklahoma credit union, Tinker Federal Credit Union, is larger than 98% of all banks headquartered in the state. That’s an unfair share of the market. Credit unions deprive the U.S. Treasury of .1 billion a year, while taxpayers in every state pick up the tab.