20 CFR 416.991: If your medical recovery was expected and you returned to work.

If your impairment was expected to improve and you returned to full-time work with no significant medical limitations and acknowledge that medical improvement has occurred, we may find that your disability ended in the month you returned to work. Unless there is evidence showing that your disability has not ended, we will use the medical and other evidence already in your file and the fact that you returned to full-time work without significant limitations to determine that you are no longer disabled.

Example:

Evidence obtained during the processing of your claim showed that you had an impairment that was expected to improve about 18 months after your disability began. We, therefore, told you that your claim would be reviewed again at that time. However, before the time arrived for your scheduled medical re-examination, you told us that you had returned to work and your impairment had improved. We reviewed your claim immediately and found that, in the 16th month after your disability began, you returned to full-time work without any significant medical restrictions. Therefore, we would find that your disability ended in the first month you returned to full-time work.