if you live in a state that opted to expand medicaid then you can enroll in medicaid at no cost. if you live in a state that did not expand medicaid then you can buy insurance on your own on the exchanges but you will not receive subsidies for the premium. you will have to pay the full cost. (only people with incomes above 100% of the poverty level receive subsidies. ) if you are uninsured you will not have to pay a penalty because of your income (or lack of) assuming that you will have no income next year.
if i had no income last year what will a health insurance plan cost me?