Nearly every employer in Utah must comply with complex testing of health and welfare benefit plans that take effect Jan. 1, 1989, according to W. Brent Maxfield and Robert D. Davis, local tax partners for Peat Marwick Main & Co.

During a seminar Wednesday in the Salt Lake Marriott, they explained the effects of Section 89 of the Internal Revenue Code. They said that if employers fail to comply with the new tax law, employees can be taxed for benefits that previously have been excluded from taxable income.