Open enrollment is the period of time when you can sign up for a health plan or switch to a different plan. It usually takes place at the end of one calendar year for health insurance that takes effect at the start of the following year.
There are only a few reasons you can generally change health plans during other times of the year. For example, if you lose your job and with it your health insurance. Another reason is if you add a new member to your family or if you move.