20 C.F.R. § 404.325
If you do not have a disabling impairment, your termination month is the third month following the month in which your impairment is not disabling even if it occurs during the trial work period or the reentitlement period. If you continue to have a disabling impairment and complete 9 months of trial work, your termination month will be the third month following the earliest month you perform substantial gainful activity or are determined able to perform substantial gainful activity; however, in no event will the termination month under these circumstances be earlier than the first month after the end of the reentitlement period described in § 404.1592a .
Example 1: You complete your trial work period in December 1999. You then work at the substantial gainful activity level and continue to do so throughout the 36 months following completion of your trial work period and thereafter. Your termination month will be January 2003, which is the first month in which you performed substantial gainful activity after the end of your 36-month reentitlement period. This is because, for individuals who have disabling impairments (see § 404.1511 ) and who work, the termination month cannot occur before the first month after the end of the 36-month reentitlement period.
Example 2: You complete your trial work period in December 1999, but you do not do work showing your ability to do substantial gainful activity during your trial work period or throughout your 36-month reentitlement period. In April 2003, 4 months after your reentitlement period ends, you become employed at work that we determine is substantial gainful activity, considering all of our rules in §§ 404.1574 and 404.1574a . Your termination month will be July 2003; that is, the third month after the earliest month you performed substantial gainful activity.
20 C.F.R. §404.325