Please provide us with more details on why the IRS is claiming it was not a 1031 and we can perhaps be of better help.
It's possible that your parents did not meet one or more of the requirements for a 1031 exchange. It sounds like since the homes were being built that they may not have spent the proceeds by the end of the 180 days.
Timothy J Folkers, CPA
Principal
Folkers, Choi & Associates
An Accountancy Corporation
18818 Teller Ave., Suite 109
Irvine, CA 92612
(949) 399-1040 ext 126 -Direct
(949) 399-1041 fax
Tim@FCA-CPA.com
www.FCA-CPA.com
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