Medicare Part B covers 100% of the cost of a flu shot once every flu season with no Part B deductible required. This is true for both Original Medicare and Medicare Advantage Plans.
Original Medicare will pay for the flu shot no matter where you get it, as long as the health care provider is enrolled in Medicare. You will pay no copay or deductible if you see a doctor or other health care provider who takes assignment. If you receive your Medicare benefits from a Medicare Advantage Plan, the plan cannot require that you get a referral for the vaccine, but it can require that you use providers in the plan’s network.
The flu season usually runs from November through April. Therefore, Medicare may cover a flu shot twice in one calendar year. For example, if you get a shot in January 2015 for the 2014/2015 flu season, you could get another shot in October 2015 for the 2015/2016 flu season.