Iowa workers' compensation premiums would decrease by nearly 5 percent on average under a proposed rate decrease filed with the Iowa Insurance Division last week. The rate filingwhich would be effective Jan. 1, 2017, proposes an overall decrease in voluntary and assigned risk rates of 4.7 percent from the current rates that became effective Jan. 1, 2016. Factors contributing to the lower rates were a decline in lost-time claim frequency in policy year 2014 and decreases in indemnity and medical severities relative to wages, according to an analysis by the National Council on Compensation Insurance Inc. NCCI is also proposing a slightly lower profit and contingency provision.