JAA/FAA pilot---if you are an FAA licensed pilot you should really know this, but I will be nice.
Depends upon what you are doing with the aircraft. Under part 121/135 you need an annual check by your company check airman. I am guessing you are just operating the aircraft for pleasure at which point you need a BFR, which has been discussed ad-nauseum elsewhere on Rotorheads.
14 CFR 61.56