How age is used to set health insurance premiums has an strong impact on affordability of premiums. Age rating has been an important issue in the ongoing health care reform debate. This Insight on the Issues was prepared for AARP’s Public Policy Institute by Linda Blumberg, Matthew Buettgens, and Bowen Garrett of the Urban Institute. It compares the implications of setting premiums for older adults at three times those for younger adults, at two times those for younger adults, and if no age variation is allowed. The analysis updates earlier analysis by the authors that analyzed the implications if older adults have rates five times those of younger adults.