As a rule of thumb, when shopping for insurance through the ‘Obamacare’ Marketplace, the less you make, the lower your premium will be (thanks to subsidies in the form of advanced premium tax credits).
The IRS definition of “modified adjusted gross income” determines eligibility for subsidies (line 4 of a Form 1040EZ or line 37 of Form 1040).
Let’s assume an annual health insurance premium of $12,500 for a family of four. If household income is $32,500 (138% of federal poverty level), the subsidy would be $11,430. At 400% of federal poverty level ($94,200), the subsidy drops to just $3,550.
As you can see, subsidies can drastically lower the amount of premium you pay. One final note. If you gain or lose income during the year, you will be responsible for the difference on your year-end tax return.