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:
SSI benefits are the benefits from the Social Security Administration (SSA) that come on the 1st of the month. If SSA finds that you have gotten too much money in your SSI benefit, they will send you a Notice of Overpayment.
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).
If you did not have healthcare coverage then you could face a tax penalty under the Affordable Care Act, known as the "Shared Responsibility Payment." But this is not true for everyone, especially low-income households.