Co-Ownership and Taxes: Who gets to claim mortgage interest, depreciation etc?

[Aaron S.]

In 2022 I bought a single family home with a VA loan. I house hacked with my partner paying half of the monthly expenses. We also had 2 roommates and we split the rental income from them every month.

After a couple of months, my partner and I decided to make her a co-owner of the house. She paid me 50% of the costs up to then for buying and maintaining the house, although she did not get added to the mortgage. The mortgage remained in my name. We moved out of the house after a few more months and rented out the remaining rooms and have been splitting the monthly rental income, cash flowing about $1,000 per month total. We continue to split all costs and efforts 50/50.

For 2022 taxes, we have a disagreement. I said that I should be entitled to claiming the mortgage interest because I am the only one responsible for the debt. I reasoned that she was in the advantageous position of owning half of the home, equity and rental income without acquiring any debt to her name, and thus I was entitled to claiming the mortgage interest because if she decided to stop paying me, I would still be responsible for the entire mortgage amount. Defaulting on the mortgage would also only negatively affect me, not her.

Her point of view is that she will have a disproportionate tax bill compared to me every year because she cannot claim mortgage interest or depreciation (let us know if we're wrong on that one). She has proposed that because she is paying (Venmo) for half of the operating expenses to include the mortgage, that for taxes I should claim all of the expenses and all of the rental income due to the complications of only me owning the mortgage. 

So, what is the fair or correct thing to do?