Although doctors are historically very hard to pin down, and network data changes daily, there are a few things you can do to ensure your doctor is in-network with your health plan:
Option 1: call their office
Not all doctors at one medical practice accept all plans offered by an insurance carrier, so you will need the specific name of your health plan and the specific name of your doctor when you call.
ex: "I would like to check if Dr. Michael Jackson is in-network with the Blue Shield Gold 80 PPO."
If you qualify for a government subsidy, you can also ask your doctor if they accept marketplace plans from your insurance carrier of choice.
ex: "I would like to check if Dr. Michael Jackson is in-network with marketplace plans with Blue Shield of California."
If you can't get a verdict on whether or not your doctor is in-network with your plan when you call their office...
Option 2: use your doctor's tax ID number to verify they're in-network with your insurance carrier
Call your doctor's office and ask for your doctor's specific tax ID number. Call your insurance carrier at their general line and give them the specific name of your plan and your doctor's tax ID number. They'll be able to tell you whether or not your doctor is in-network.