20 CFR §404.1592c

1. (a)You can have your entitlement to benefits reinstated under expedited reinstatement if—
   1. (1)You were previously entitled to a disability benefit on your own record of earnings as indicated in § 404.315, or as a disabled widow or widower as indicated in § 404.335, or as a disabled child as indicated in § 404.350, or to Medicare entitlement based on disability and Medicare qualified government employment as indicated in 42 CFR 406.15;
   2. (2)Your disability entitlement referred to in paragraph (a)(1) of this section was terminated because you did substantial gainful activity;
   3. (3)You file your request for reinstatement timely under § 404.1592d; and
   4. (4)In the month you file your request for reinstatement—
      1. (i)You are not able or become unable to do substantial gainful activity because of your medical condition as determined under paragraph (c) of this section;
      2. (ii)Your current impairment is the same as or related to the impairment that we used as the basis for your previous entitlement referred to in paragraph (a)(2) of this section; and
      3. (iii)You are disabled, as determined under the medical improvement review standard in §§ 404.1594(a) through (e).
2. (b)You are entitled to reinstatement on the record of an insured person who is or has been reinstated if—
   1. (1)You were previously entitled to one of the following benefits on the record of the insured person—
      1. (i)A spouse or divorced spouse benefit under §§ 404.330 and 404.331;
      2. (ii)A child's benefit under § 404.350; or
      3. (iii)A parent's benefit under § 404.370;
   2. (2)You were entitled to benefits on the record when we terminated the insured person's entitlement;
   3. (3)You meet the requirements for entitlement to the benefit described in the applicable paragraph (b)(1)(i) through (b)(1)(iii) of this section; and
   4. (4)You request to be reinstated.
3. (c)We will determine that you are not able to do substantial gainful activity because of your medical condition, under paragraph (a)(4)(i) of this section, when:
   1. (1)You certify under § 404.1592d(d)(2) that you are unable to do substantial gainful activity because of your medical condition;
   2. (2)You are not able or become unable to do substantial gainful activity in the month you file your request for reinstatement; and
   3. (3)We determine that you are disabled under paragraph (a)(4)(iii) of this section.