Assumed a Mortgage Promissory Note, Deed not transferred til now. Tax implications?

My wife and I have been living for the past 5 years in a house owned by my in-laws in a rent-to-own situation.

 

The cost of the 'rent' was the same as the cost of the mortgage. We've also been the ones responsible for all utilities and repairs. My in-laws received the payment and paid the bill.

 

My father-in-law passed away last year (Spring 2022). My wife and I went through an Assumption of Promissory Note process (Summer 2022). Here, we became the responsible party for paying the mortgage. Rent-to-own was done. Cost of house was $60,000 at purchase (a huge fixer upper) with a 0% interest seller-financed mortgage. Balance of house was ~$30,000 at Summer 2022.

 

It was only in the past few weeks that I realized our name was not updated on the Title / Deed (Arizona). We went through a title company and the title / deed has been transferred to our name.

 

I've read recently about equitable ownership. I'm trying to understand what I can claim on our 2022 taxes. Because it's 0% interest, there will be no mortgage interest deduction. But there were energy efficiency upgrades.

 

We did not pay my mother-in-law anything to buy her out. We just took over the responsibility to pay the mortgage. The deed transfer was from my Mother-in-law. The Title agency that is filing the papers called it a simple deed transfer without escrow. We were legally allowed to do the Assumption because of the passing away of my father-in-law. She is the executor of his estate and it was fully jointly owned.