The estimated average contribution rate of Iowa employers to the state unemployment compensation fund will increase to 1.57 percent in 2016 from 1.24 percent this year, according to a release from Iowa Workforce Development (IWD). The unemployment insurance rate table trigger formula is primarily based on the trust fund balance, unemployment benefit payment history and covered wage growth. The formula is designed to enable the trust fund to keep pace with potential liabilities as covered employment and wages grow. IWD Director Beth Townsend said in the release that “a large number of zero-rated employers and new, non-construction employers continue to pay 1 percent, one of the lowest tax rates in the country.”