Yes, in most states you can, within limits. Federal rules allow insurers offering marketplace plans to charge older adults (e.g., in their sixties) up to three times the premium they would charge younger adults (e.g., in their early twenties). Outside the marketplace, not all plans must follow the same rules for premiums based on age. (45 C.F.R. § 147.102; 82 Fed. Reg. 18346, April 18, 2017).