An employing unit not qualifying as a covered employer under any other section of this law shall be a liable employer if together with one or more employing units owned or controlled by the same interest, the combined employment or quarterly gross wages (counting together the number of workers or the combined gross quarterly wages of each enterprise) would total one or more workers in a portion of a day in each of 20 different weeks or have a combined gross quarterly payroll which equals or exceeds $1,500 in a calendar quarter.
Iowa Admin. Code r. 871-23.23