you would need to check with your former employer's human resources office. if you were a federal employee this would be the office of personnel management. generally if you give up retiree health care you cannot go back on it at a later date. you can still go on your state's exchange/marketplace to see how much coverage is through an individual policy and may find something cheaper but you may put your retiree insurance at risk.
i currently have a good health insurance plan with cigna but i don't like their politics. . as a retired government worker i'm currently paying about $320 per month for my husband and me to have major medical. can i switch to a policy under the aca and then go back to cigna if i don't like the new program?