Mine is supposed to be once a year. It was due in March. I don't like the guy at my LQS very well. The shop is closing and I was going to take it in but another shop the next town over is going to take over as the Bernina Shop and her DH is going to Bernina Repair University. So I will take it in September to let him clean it. The computerized machine want to be seen annually, it even tells me!!