Not usually.

Once your plan starts, you will need to continue with that plan or no Marketplace coverage at all. You cannot decide that you like a different plan better and want to make a switch.

The exception to this is if you move to an area where you current plan is no longer available. In this case, you would qualify for a SEP and have the opportunity to select a new health plan.

You do have the option to drop any current health plan you have simply by not paying the monthly premium or by calling the insurance company directly and terminating coverage. Doing so however will not trigger a loss of coverage SEP.