12/15/2017，超过75万的利息部分不能抵税，75万以下的利息还是可以抵税的。

一般是看closingdate，但是有binding contract exception

 

(IV) BINDING CONTRACT EX- 13 CEPTION.—In the case of a taxpayer 14 who enters into a written binding con- 15 tract before December 15, 2017, to 16 close on the purchase of a principal 17 residence before January 1, 2018, and 18 who purchases such residence before 19 April 1, 2018, subclause (III) shall be 20 applied by substituting ‘April 1, 2018’ 21 for ‘December 15, 2017’.