If you qualify for a health coverage exemption, you don’t have to pay the fee for the months you didn’t have health coverage.
Note: Starting with the 2019 plan year (for which you’ll file taxes in April 2020), the penalty no longer applies. (The fee is sometimes called the “Shared Responsibility Payment” or “mandate.”) If you don’t have coverage during 2019 or later, you don’t need an exemption in order to avoid the penalty.
If you need exemption information for years prior to 2019 you can find more information on how to apply for an exemption through healthcare.gov