92 STAT. 3178
PUBLIC LAW 95-618—NOV. 9, 1978
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" ( i i) establish a procedure under which a manufact u r e r of an item may request the Secretary to certify that the item will be treated, for purposes of this section, as insulation, a n energy-conserving component, o r renewable energy source property. " (B) CONSULTATION.—Performance and quality standards regulations and other regulations shall be prescribed by the Secretary under paragraph s (3), (4), and (5) and under this paragraph only after consultation with the Secretary of Energy, the Secretary of Housing and Urban Development, and other appropriate Federal officers.
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" (7) W H E N EXPENDITURES MADE; AMOUNT OF EXPENDITURES.—
" (A) IN GENERAL.—Except as provided in subparagraph (B), an expenditure with respect to an item shall be treated as made when original installation of the item is completed.
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"(B)
RENEWABLE ENERGY SOURCE EXPENDITURES.—In the
case of renewable energy source expenditures in connection with the construction or reconstruction of a dwelling, such expenditures shall be treated as made when the original use of the constructed o r reconstructed dwelling by the taxpayer begins. " (C) A M O U N T. — The amount of any expenditure shall be the cost thereof.
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" (D) ALLOCATION I N CERTAIN CASES.—If less than 80 per-
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cent of the use of a n item is for nonbusiness residential purposes, only that portion of the expenditures for such item which is properly allocable to use for nonbusiness residential purposes shall be taken into account. For purposes of this subparagraph, use for a swimming pool shall be treated as use which is not for residential purposes. " (8) P R I N C I P A L RESIDENCE.—The determination of w h e the r or
26 USC 1034. •
not a dwelling unit is a taxpayer's princiDal residence shall be made under principles similar to those applicable to section 1034, except that— " (A) n o ownership requirement shall be imposed, and " (B) the period for which a dwelling is treated as the principal residence of the taxpayer shall include the 30-day period ending on the first d a y on which it would ( b u t for this subparagraph) be treated as his principal residence. '* (d) SPECIAL RULES. — For purposes of t h i s section— " (1) DOLLAR AMOUNTS I N CASE o r JOINT OCCUPANCY.—In the case
of any dwelling unit which is jointly occupied and used during any calendar year as a principal residence by 2 or more individuals— " (A) the amount of the credit allowable under subsection (a) by reason of energy conservation expenditures or by reason of renewable energy source expenditures (as the case may be) made during such calendar year by any of such individuals with respect to such dwelling unit shall be determined by treating all of such individuals as one taxpayer whose taxable year is such calendar year; and ,* '. " (B) there shall be allowable with respect to such expenditures to each of such individuals a credit under subsection (a) for the taxable year in which such calendar year ends in an amount which bears the same ratio to the amount determined under subparagraph (A) as the amount of such expenditures ^ made by such individual during such calendar year bears to
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