as being equal to the monthly specified child allowance which would be determined under section 24A(b) with respect to such taxpayer for such calendar month if— (1) unless determined by the Secretary based on any information known to the Secretary, the only specified children of such taxpayer for such calendar month are the specified children of such taxpayer for the reference month, (2) unless determined by the Secretary based on any information known to the Secretary, the ages of such children (and the status of such children as specified children) are determined for such calendar month by taking into account the passage of time since such reference month, (3) the limitations of section 24A(b)(2) were applied with respect to the reference taxable year rather than with respect to the applicable taxable year, and (4) unless determined by the Secretary based on any information known to the Secretary, no monthly specified child allowance were determined with respect to such taxpayer for such calendar month unless the taxpayer (in the case of a joint return, either spouse) has a principal place of abode (determined as provided in section 32) in the United States or Puerto Rico for more than one-half of the reference month. (c) Presumptive eligibility (1) In general An individual shall be treated as a specified child of a taxpayer for purposes of determining any monthly advance child payment under this section only if such month is part of the period of presumptive eligibility determined by the Secretary under this subsection with respect to such specified child and such taxpayer (determined by treating the month described in subclause (I) of paragraph (2)(A)(ii) as being the first month beginning after the determination described in such subclause). (2) Period of presumptive eligibility For purposes of this section— (A) In general Except as otherwise provided by the Secretary, the term period of presumptive eligibility means the period— (i) beginning with the month for which presumptive eligibility is established,