Until the end of 2018, the ACA required that all US taxpayers had to have health insurance that met a minimum standard. Some taxpayers are eligible for exemptions from this due to certain life events, financial status or other factors. If you had affordable health care options open to you and you chose not to avail of health insurance, then you would have to pay a fee when filing your taxes
What happens if I didn't have health coverage in 2018 or have an exemption?
In this instance, you may still have to pay a fee to file your taxes in April 2019. To find out more, I will refer you to HealthCare.gov to find out more about exemptions