i attached a link to IRS 2025 (nothing changed from the 2024 pub) PUB 935 which contains the rules for the deduction and a worksheet. read the pub in its entireity and if you have questions post them back in this thread
https://www.irs.gov/pub/irs-pdf/p936.pdf
what's missing is a clear explanation if you refinanced the property for more than the existing debt at that time. Qualified mortgage debt is only the amount that's the same as the refinanced amount unless you used the excess to buy, build or substantially improve the property. Multiple refis can present a problem in determining the eligible amount,
