@Customer1001 Yes, you can take the interest as a deduction on your Schedule E, Rent/Royalty Income & Expense Form, from the date it was actually a rental (you were no longer living there and have listed it as for rent, or of course, have already signed a lease agreement - this obviously is showing that you are not trying to write off the interest during a "down time" of the conversion from residence to rental.
If you moved out and converted as of July - as you were converting during June (per your statements above) - for that first year. If this is not what you did, then it would definitely be worth it to amend your return(s) from 2018 and 2019! Even if in those years you are not seeing the full benefits (for whatever other reasons due to your other tax items), this is being recorded and carried forward from year to year and when you sell the property (if you ever sell), you will then be able to reap some of these "disallowed losses" that you will be carrying forward from 2018 until you do sell it.
