You may qualify for a premium tax credit which is based on income and family size. To qualify, your family income must fall between 100 and 400 percent of the federal poverty level (FPL).
That means, for example, a family of four with an income between $24,300 and $97,200 in coverage year 2017 would qualify for these credits. (The government uses FPL standards from the previous year to determine eligibility.) For 2018 coverage for a family of four, the income bracket adjusts to $24,600 to $98,400.
If you qualify, the credits can be applied to your monthly insurance premiums. If your income changes during the year and you no longer qualify for the credits when you file your taxes, you will have to repay.