Joint Tenancy and dividing mortgage interest

[DragonVT]

I bought a home this year with my girlfriend.  We both use the property as our primary residence.  She has children and I do not.  We are not married, so we are filing separately.  She is filing as head of household with her kids as dependents, and I am filing as single.  Because she is filing as head of household, her standard deduction is larger than her itemizations, so she will not be itemizing her return.  I am itemizing my return.

The 1098 for the property shows both of our names, but only my SSN, making me the payer of record.  Since she is not itemizing her return, am I free to claim the full mortgage interest as a deduction on my tax return? The only information I can find from the IRS on this matter is from Publication 936 and reads as follows:

"More than one borrower. If you and at least one other person (other than your spouse if you file a joint return) were liable for and paid interest on a mortgage that was for your home, and the other person received a Form 1098 showing the interest that was paid during the year, at-tach a statement to your paper return explaining this. Show how much of the interest each of you paid, and give the name and address of the per-son who received the form. Deduct your share of the interest on Schedule A (Form 1040), line 8b, and print “See attached” next to the line. Also, deduct your share of any qualified mort-gage insurance premiums on Schedule A (Form 1040), line 8d.
Similarly, if you're the payer of record on a mortgage on which there are other borrowers entitled to a deduction for the interest shown on the Form 1098 you received, deduct only your share of the interest on Schedule A (Form 1040), line 8a. Let each of the other borrowers know what his or her share is."

I don't see anything that stipulates max or min percentages, or that interest claimed has to tie to ownership share of the property.  Is there any further explanation or requirement placed on mortgage interest?  Is there another policy or document with further details?  Can we split the interest in whichever way we deem appropriate, so long as the joint total we claim as a deduction doesn't exceed the interest paid in Box 1 on the 1098?

[LeonardS]

No, you can only deduct the amount of interest that you paid. You can not claim a deduction for the amount your girlfriend paid.  This would apply also to real estate taxes.

[DragonVT]

OK, thank you for the quick response!  Can you help me understand where this is explained in the tax code?  I'm having a hard time locating anything specific about joint tenancy and mortgage interest deductions, other than the two short paragraphs I referenced.  I'd really like to get a better understanding of how this is defined and structured.  Thanks is advance!

[LeonardS]

"...If you and at least one other person (other than your spouse if you file a joint return) were liable for and paid interest on a mortgage that was for your home, and the other person received a Form 1098 showing the interest that was paid during the year, attach a statement to your paper return explaining this. Show how much of the interest each of you paid, and give the name and address of the person who received the form. Deduct your share of the interest on Schedule A (Form 1040), line 8b, and print “See attached” next to the line. Also, deduct your share of any qualified mortgage insurance premiums on Schedule A (Form 1040), line 8d."

Ref IRS  Publication 936

[DragonVT]

Yes, I read and followed that section, but that doesn't seem to apply to us.  She did not receive a 1098, I am the only one that received one.  The next section down says, "Similarly, if you're the payer of record on a mortgage on which there are other borrowers entitled to a deduction for the interest shown on the Form 1098 you received, deduct only your share of the interest on Schedule A (Form 1040), line 8a. Let each of the other borrowers know what his or her share is."

This would seem to imply that there is no set and required division, and that it is up to the payer of record to communicate and define share among the other borrowers.  That's part of why I asked if there was a more specific and defined section of the tax code that covers this information.  These two paragraphs seem somewhat ambiguous and open to interpretation.  I'm not saying you're incorrect, I'm saying I'd like a more specific definition in writing of what is and is not allowed, and how share is defined.  For starters, if we are paying the mortgage and other bills with comingled funds, how can you readily define and prove who paid what?  Was it my money or hers that paid the mortgage?  Did she pay for the groceries or did I?  As written, this seems like a gray area, and I'd like to better understand the boundaries.

[AmyC]

Home ownership can vary by great amounts. Suppose 10 of you own the house? Maybe a corporation with a 1,000 investors? You simply take the portion that relates to what you own. If only two of you own the house then you should know. Who put down how much? Who pays what? There are calculators online to help if you are not  Joint tenants with rights of survivorship - that would be 50/50. Otherwise, see below.

See:

How to Calculate the Percentage Ownership of a Tenant in ...

Tenants in Common Not 50/50 - Home Guides