My co-owner and i are on the single family home's title. Only my name is on the loan. My co-owner pays for the mortgage and claims the mortgage interest deduction on his income tax. My CPA said that only the person on the mortgage can claim the mortgage i

Who lives in the home?

My co-owner.

Please help to send me the IRS article showing who can claim for the mortgage. Thanks!

<a rel="nofollow" target="_blank" href="https://www.law.cornell.edu/cfr/text/26/1.163-1">https://www.law.cornell.edu/cfr/text/26/1.163-1</a>

Excellent! Your answer was very helpful. I sent it to my CPA and she has agreed to it. Thank you very much for your expert advice.

In most instances, interest can be deducted only by the person or entity that is legally responsible for the debt. However,  a potential exception appears in Regs. Sec. 1.163-1(b), which states:

Interest paid by the taxpayer on a mortgage upon real estate of which he is the legal  or equitable owner  , even though the taxpayer is not directly liable upon the bond or note secured by the mortgage, may be deducted as interest on his indebtedness. 

https://www.thetaxadviser.com/issues/2012/jan/tpp-jan12-story-01.html

There have been numerous Tax Court cases since then, affirming this concept, of which your CPA should be aware.

It's clear, from the fact of your situation,  that your co-owner is an equitable owner and can claim the deduction.