26 CFR § 1.1015-5 - Increased basis for gift tax paid.
https://www.law.cornell.edu/cfr/text/26/1.1015-5
The increased basis of property after first sale/gift would be the fair market value of the property
https://www.law.cornell.edu/cfr/text/26/1.1015-5
The increased basis of property after first sale/gift would be the fair market value of the property