For which home would the taxpayer be able to fully deduct mortgage interest as of 2018?

As of 2018, taxpayers can fully deduct mortgage interest on their primary residence and a second home, as long as the loans used to purchase or improve the homes have a combined value of up to $750,000 (or $375,000 if married filing separately). This means that the taxpayer can deduct mortgage interest for a primary residence and a second home as long as the loans on both properties do not exceed the specified limits. It's important to note that any loans beyond these limits may result in a partial deduction or no deduction at all for mortgage interest.

As of 2018, the taxpayer would be able to fully deduct mortgage interest for the following types of homes:

1. Primary Residence: The mortgage interest on a loan used to purchase, build, or improve the taxpayer's primary residence can be fully deductible. The loan must be secured by the primary residence itself.

2. Second Home: If the taxpayer has a second home, such as a vacation home, they can also fully deduct the mortgage interest on a loan used to purchase, build, or improve that second home. However, there are some limitations. The combined outstanding mortgage debt on both the primary residence and the second home cannot exceed $750,000 if married filing jointly ($375,000 if married filing separately).

Please note that these deductions are subject to certain limitations and restrictions, and it is always recommended to consult with a tax professional or refer to the official IRS guidelines for the most accurate and up-to-date information.