It all depends upon your certificate and who holds the responsibility with the Registrar. If you are hiring your registrar on your own then your documents (agreements made) with your registrar will define the initial registration audit and the surveillance audits to follow (depending upon the product or service risk and or the Customer they can be anywhere from every 18 mo to 1-2 times per year, generally speaking.
If you are part of a larger scheme (International Registration with a primary corporate certificate holder in another country) then you might not see a registrar audit but once every few years (depending upon the contract), However be warned, your internal audit system best be very robust for this type of system, because your entire companies registration hangs in the balance should your division be the cause of a major Non-Conformity. Its usually a career decision not to have a robust internal audit system in this type of mufti corporate site registration.