5 U.S.C. § 8443: Rights of a child

the amount by which the applicable amount under paragraph (2) for such month exceeds the applicable amount under paragraph (3) for such month, divided by the number of children entitled to a payment under this section for such month. The applicable amount under this paragraph for any month is the total amount to which the surviving child or children (as the case may be) of the annuitant, employee, or Member would be entitled for such month under subchapter III of chapter 83 (including any adjustment based on section 8340) based on the service of such annuitant, employee, or Member, if the service of such annuitant, employee, or Member were creditable under such subchapter. The applicable amount under this paragraph for any month is the total amount of child’s insurance benefits which are payable (or would, on proper application, be payable) under title II of the Social Security Act for such month based on the wages and self-employment income of such annuitant, employee, or Member. commences on the day after the annuitant, employee, or Member dies; commences or resumes on the first day of the month in which the child later becomes or again becomes a student as described by section 8441(4), if any lump sum paid is returned to the Fund; or commences or resumes on the first day of the month in which the child later becomes or again becomes incapable of self-support because of a mental or physical disability incurred before age 18 (or a later recurrence of such disability), if any lump sum paid is returned to the Fund. becomes 18 years of age unless then a student as described or incapable of self-support; becomes capable of self-support after becoming 18 years of age unless then such a student; becomes 22 years of age if then such a student and capable of self-support; ceases to be such a student after becoming 18 years of age unless then incapable of self-support; or dies or marries;