The penalty for not having minimum essential coverage is either a flat amount, or a percentage of household income, whichever is greater.
For 2018 the flat amount is $695 for each uninsured adult and $347.50 for each uninsured child, up to $2,085 per family. The percentage penalty is 2.5% of family income above the federal tax filing threshold, which is $12,000 for a single filer, $24,000 for people who file jointly in 2018. The percentage penalty is also capped at an amount equal to the national average bronze health plan premium available through the Marketplace. That amount is updated annually in the instructions for IRS Form 8965.
The penalty is based on “coverage months.” This means that each month you are uninsured in 2018, you may owe 1/12th of the annual penalty. However, short spells of uninsurance may not be subject to a penalty.
For 2018, if you think you may owe a penalty for not being insured, you can claim a hardship exemption if you experienced circumstances that made it hard for you to get coverage. With this exemption, you will not owe a tax penalty. You can claim the hardship exemption right on your tax return by checking a box on Form 1040. You will not be required to submit any documentation of the hardship with your tax return, though you should retain any documentation for your own records.
For more information about the penalty in 2018, also called the individual responsibility payment, see instructions for Form 8965 on the IRS web site.