The final bill reduces the limit on deductible mortgage debt to $750,000 for new loans taken out after 12/14/2017. Current loans of up to $1 million are grandfathered and are not subject to the new $750,000 cap. Neither limit is indexed for inflation.
Homeowners may refinance mortgage debts existing on 12/14/2017 up to $1 million and still deduct the interest, so long as the new loan does not exceed the amount of the mortgage being refinanced.
The final bill repeals the deduction for interest paid on home equity debt through 12/31/2025. Interest is still deductible on home equity loans (or second mortgages) if the proceeds are used to substantially improve the residence.
Interest remains deductible on second homes, but subject to the $1 million / $750,000 limits.
References for you
Here are some references for understanding Mortgage Interest Deduction Basics
Mortgage Interest Deduction Basics
What REALTORS® Need to Know About the New Tax Law (National Association of REALTORS®, Feb. 25, 2019)
As Mortgage-Interest Deduction Vanishes, Housing Market Offers a Shrug(link is external) (The New York Times, Aug. 4, 2019)
The Tax Change Wild Card(link is external) (REALTOR® Magazine, Mar.-Apr. 2019)
Calculating the Mortgage Interest Tax Deduction(link is external) (Investopedia, Feb. 16, 2019)
How Does the Mortgage Interest Deduction Benefit Housing and Homeownership?
Why Homeownership Should Continue to Be Incentivized by Our Federal Tax System (Rosen Consulting Group/National Association of REALTORS®, Feb. 2020)
7 Tax Benefits of Owning a Home: a Complete Guide for Filing in 2020(link is external) (realtor.com®, Feb. 3, 2020)
Study Finds Americans Prefer Tax Credits to Government Checks(link is external) (Yale News, May 7, 2019)
How Tax Reform Changed the Market's Outlook(link is external) (National Mortgage News, May 2019) E
The TCJA Versus Home Ownership(link is external) (Accounting Today, Jan. 29, 2019