Many states are considering legislation requiring private insurance companies to pay for autism-related services. Arguments against mandates include that they will result in higher premiums. Using Pennsylvania legislation as an example, which proposed covering services up to $36,000 per year for individuals less than 21 years of age, this paper estimates potential premium increases. The estimate relies on autism treated prevalence, the number of individuals insured by affected plans, mean annual autism expenditures, administrative costs, medical loss ratio, and total insurer revenue. Current treated prevalence and expenditures suggests that premium increases would approximate 1%, with a lower bound of 0.19% and an upper bound of 2.31%. Policy makers can use these results to assess the cost-effectiveness of similar legislation.