One of the challenges for those who have Medigap plans is what to do if the premiums go up, and they can no longer afford the policy. One option is to switch to another less expensive Medigap plan. However, in most cases, to do that, you will have to undergo medical underwriting and which could increase your rates, or the insurance company could decline your application altogether. A popular option for those moving from a Medigap plan that is too expensive is to enroll in a Medicare Advantage plan. Most Medicare Advantage plans have physician and hospital networks you must stay within. This is the most significant difference between Medigap and Medicare Advantage plans. If your doctor is in-network, though, you should not have any issues, and you will likely get additional benefits on top of those provided by original Medicare and your Medigap plan at a lower cost.