NOTE: This information is offered by the IRS for Tax Year 2017. This includes both rules for making the payment (if you don't have health insurance) and rules about who is "exempt" (does not have to pay). Many people with very low incomes and people with certain immigrant statuses do not have to pay.
Some low income people are eligible for Mainecare. Most other people with low incomes can get help paying for health insurance. The IRS gives instant tax credits to help with the cost. There are many places to get help finding health insurance: