Bought a house with my sibling and we obviously file separate. How would mortgage interest breakdown? Do we claim half each or does 1 person claim all of it?

It depends.  There are different situations that affect how you deduct mortgage interest when co-owning a home.

• The 1098 has multiple names, but only one person is paying the mortgage/interest: Only the person who actually paid the interest can take the deduction.
• The 1098 has multiple names and multiple people are paying the mortgage/interest: Each can deduct their portion of interest paid. When entering the 1098 only enter the amount that you actually paid, not the full amount.
• The 1098 is in someone else's name (not a seller-financed loan), but you pay some or all of the mortgage/interest: In most cases you'd have to be the owner of the property to take the deduction. If you can prove you're the owner in every way but in name (constructive ownership), you could still be allowed to take the deduction.  (You could get audited and have to prove constructive ownership. If the IRS doesn't allow the deduction, you may have to go to tax court and argue your case.)   You’ll be able to explain in TurboTax why you’re taking the deduction. In the Deductions & Credits section (where you enter mortgage interest), check The interest amount I entered is different than what's on my 1098 when entering your info.

Co-owners mortgage interest