File it as soon as you notice, and include the period in your next submission if the deadline has passed. A missed update earns a penalty point rather than a fine, and points expire after a run of on-time filing, so the recovery path is straightforward: get current, then stay current. What you should not do is decide the quarter is lost and skip to the next one, because the point stands and you have not fixed the underlying gap in your records. If you are several quarters behind — which we see, particularly with clients who set up and then drifted — we will get you caught up and, where there is a reasonable excuse such as illness or bereavement, appeal the points on your behalf.