Insurance Commissioner Joseph Murphy said Thursday the decision means rates will be unchanged on Sept. 1, saving employers in Massachusetts an estimated $200 million that would have gone toward higher premiums.
The 18.8 percent increase was sought by the Workers' Compensation rating and Inspection Bureau, a consortium of licensed insurers in the state.
Murphy said regulators could not justify the proposed hike after analyzing information presented during a five-month hearing process.
Workers compensation provides coverage for health care costs and lost wages for workers injured on the job. Businesses are required to carry workers comp insurance.