I am moving from NC to WA and I am wondering if I can keep my NC health plan under the ACA.
When you move whether or not you keep your coverage depends upon your plan type and if you have more than one residence. When you move you can use special enrollment to switch plans, but if won't be in one spot long, are traveling, or are near the end of the policy you may simply want to keep your plan. Generally plans and their networks are based on region. So your HMO from NC isn't going to do much in WA. However a multi-state PPO is going to function pretty much the same wherever.
If you get assistance through the Marketplace or Medicaid, then there is another layer of complications. Once you move to a new state that means you are no longer a resident of the state that was issuing assistance. On marketplace plans you can talk to your insurer to find out options, but generally the simplest move is to just enroll in a new plan either during open enrollment or through special enrollment. The big downside of switching plans is that you lose the amounts you paid into cost sharing on the plan (this can potentially be avoided by calling your insurer).
There is no one right answer, but generally 1) switch coverage if you haven't paid much in toward cost sharing 2) keep your coverage if you have a multi-state plan (especially if you still have a residence in the state you are moving from. 3) make sure to talk to your insurer before you move, and make sure to take advantage of special enrollment when moving outside of open enrollment.