I believe the taxpayer would be safe to rely on the above based on the Statute.
IRC Section 25D(e)(8)(B) states "in the case of an expenditure in connection with the construction or reconstruction of a structure, such expenditure shall be treated as made when the original use of the constructed or reconstructed structure by the taxpayer begins."
As noted above, as long as the builder has not claimed the credit, the purchaser of the home should qualify as the buyer is the "taxpayer" that starts the original use requirement.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
