A proposed change to a federal credit union's sponsoring organization's membership has raised questions about whether the federal credit union's field of membership will still meet NCUA regulations.

If  Thrivent Federal Credit Union's sponsor broadens its common bond, the credit union will have to submit its sponsor's new bylaws to the NCUA for review to make sure its field of membership remains in compliance with the agency's regulations, according to a letter from the agency.

Thrivent Financial for Lutherans, the $75 billion insurance and financial services mutual company sponsors the $478 million 45,000-member Thrivent FCU, which it formed last year from the consumer lending and deposit business of a bank that it also owns. The sponsoring firm's members face a vote starting in March about whether to expand the common bond for membership from Lutheran to Christian, raising the possibility that it might also sharply expand the credit union's field of membership.