Zenith National Insurance Corp. said that its subsidiary, Zenith Insurance Company, has filed with the California Department of Insurance on Thursday to adjust its California workers’ compensation insurance rates for policies starting or renewing on or after July 1.

The new rates for Woodland Hills-based Zenith represent an average reduction of 5 percent when compared to rates in effect since Jan. 1.

“Continued deflationary cost trends make rate reductions appropriate,” Chairman Stanley R. Zax said in a statement.