(a) The sum of the rates of assessment for the surcharge imposed by this chapter and the surcharges imposed by Chapters 403 and 405, Labor Code, set by the commissioner, may not exceed 2.7 percent of the gross premiums subject to surcharges.
(b) The commissioner shall annually adjust the rate of assessment of the surcharge so that the surcharge imposed that year, together with any unexpended funds produced by the surcharge, produces the amount the commissioner determines is necessary to pay the expenses during the succeeding year of regulating workers' compensation insurance.