mortgage interest deduction calculation

Hello sfl85, 

Since the principal amount of your mortgage exceeds $750,000, the amount of interest that you can deduct will be limited. You can use any online mortgage interest calculator to determine the amount of interest paid for the year, then apply the limitations using this article: Deducting Mortgage Interest FAQs

You can always reach out for live help from a TurboTax agent when preparing your return for additional assistance in this area. 

Thanks for the reply! 

Say the interest rate is very high. Is there a limitation on the total amount of interest paid on the $750,000 loan?  

No deduction limitation of the interest paid on the principal balance of $750,000, even if the interest rate is high.