You misunderstood. The $10,000 limit is for SALT--state and local taxes.
State, local, property, and sales tax (SALT) deductionFor mortgages in 2018:
- If you itemize, you can deduct the interest on up to $750,000 in mortgage debt, if the loan was used to buy or improve a first or second home.
- Mortgages and refinances taken out before December 16, 2017 are grandfathered in at the $1 million debt limit.
- You can still deduct the interest on a new or existing home equity loan or line of credit, but only if it’s used to buy, build, or substantially improve your home and your total mortgage debt doesn’t exceed $750,000.
https://ttlc.intuit.com/questions/4482394-how-will-tax-reform-affect-my-2018-federal-tax-return
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