Fannie Mae (FNMA) and Freddie Mac were sued for unpaid transfer taxes by a Maryland county, which argued in a federal court filing that the home-mortgage finance companies can’t claim a government exemption from property fees.

Fannie Mae and Freddie Mac aren’t qualified for the exemption because they have been federally chartered, publicly traded, private-stock corporations since March 31, 2003, according to the complaint filed by Montgomery County yesterday in U.S. District Court in Beltsville, Maryland.