principal residence

(3)The term “principal residence” has the same meaning as when used in section 121. (d)If the credit allowable under subsection (a) exceeds the limitation imposed by section 26(a) for such taxable year reduced by the sum of the credits allowable under subpart A of part IV of subchapter A (other than this section and section 25D), such excess shall be carried to the succeeding taxable year and added to the credit allowable under subsection (a) for such taxable year. (e)For purposes of this section—


26 USC § 1400C(c)(3)

Scoping language

when used in section 121
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