Construction Loans and Mortgage Interest

[Larry Martin]

If a person is building a new home while living in his/her primary
residence (for which mortgage interest is claimed), does the interest on
the construction loan qualify as deductible mortgage interest on a
second home?

If so, how is it claimed? Do you add the yearly interest from the
current primary residence to the interest on the new residence being
built and enter them both on the same line on Schedule A? The same for
property taxes. Is it necessary to file an explanatory statement with
the IRS?

Thanks in advance.