关键是你重贷的时候如果还是自住房，不能减。

refinancing cost for rental property can be deducted over the life of the loan, see: 

https://ttlc.intuit.com/community/credits-and-deductions/help/what-can-i-deduct-when-refinancing-rental-property/00/25982#:~:text=The%20costs%20associated%20with%20obtaining,for%20the%20next%2030%20years.

Your problem is, when you refinanced 8 times, how many times was it refinanced during your house being a rental?  My guess is zero.  

The last refinance happened during the year when you convert primary residence to rental, so maybe you can argue the last refinance is in preparation for renting so that might count.  But the previous 7 times definitely cannot be deducted until you sell the house.