One Mortgage Form, Two Borrowers

One Form 1098 may report interest paid by two borrowers. The name printed on the form does not, by itself, decide who gets the whole deduction. This guide uses the IRS’s 2025 return instructions; check the instructions for the year you are filing.

A two-borrower example

Fictional 2025: unmarried co-owners Alex and Blair are both liable on a mortgage secured by their qualified main home. They itemize, satisfy all mortgage-interest requirements and limits, and have no adjustments. Alex paid $8,000 of interest and Blair paid $4,000. Alex receives Form 1098 showing $12,000.

Under Publication 936’s multiple-borrower instructions, Alex reports only $8,000 on Schedule A line 8a and informs Blair of the shares. Blair reports $4,000 on line 8b. For a paper return, Blair writes “See attached” beside that line and attaches an explanation showing each person’s interest paid and Alex’s name and address. Check the software’s e-filing procedure separately.

Eligibility comes before splitting a number

The IRS’s co-owner FAQ says that taxpayers generally must be legally obligated to pay the expense and must have paid it during the year. Its equal-share example concerns two eligible legal owners who are jointly and severally liable and pay equally from a joint account in which they have equal interests.

That example is not permission for every pair of borrowers to choose a 50–50 split. Keep records of when the mortgage was acquired, how its proceeds were used and how the interest payments were divided. Joint accounts, reimbursements or unequal contributions may require a closer review of the facts.

Check the mortgage, not just the information form

IRS Topic 505 explains that qualified home-mortgage interest is an itemized deduction and concerns a loan secured by a main or qualifying second home. Debt limits and the use of the borrowed funds matter. For home-acquisition borrowing, check that the funds were used to buy, build or substantially improve the home securing the loan.

Do not treat every amount on a mortgage statement as deductible interest or assume that sharing payments removes the deduction limits. Ask a qualified tax professional to review unusual ownership, loan-use or payment arrangements before applying the simple example.

Reconcile the records before preparing either return

Start with a folder containing the annual interest statement and the underlying payment records. Make a worksheet with the payment date, total transfer, interest component and person who paid. Put principal, escrow deposits and other charges in separate columns so they do not accidentally enter your interest total.

Use the servicer’s allocation rather than estimating interest as a fixed percentage of each bank withdrawal. If you cannot connect a transfer to the mortgage record, mark it unresolved and ask for the missing detail. A neat spreadsheet is not reliable if its inputs are guesses.

For a bookkeeping check, suppose Alex’s monthly records total $7,600 but the draft worksheet says $8,000. The $400 difference needs an explanation before the return is prepared. It might reflect a missing document or an entry error; the calculation alone does not tell you which.

Similarly, $8,000 plus $4,000 equals the $12,000 annual statement in the opening example. That agreement checks the arithmetic, not the tax eligibility. Keep both questions visible: do the records reconcile, and does the claimed interest satisfy the applicable rules?

Coordinate without exposing an entire tax return

Give each preparer the same reconciled mortgage worksheet and relevant supporting documents. If one person’s preparer finds a discrepancy, update the shared worksheet and label the version rather than letting two different totals circulate.

Limit the exchange to information needed for the mortgage question. A co-owner does not automatically need your complete tax return, income documents or unrelated bank transactions. Use a secure method for records containing account information and confirm the recipient before sending them.

A helpful cover note can say: “These are the payment records supporting the proposed allocation. Please check eligibility, limits and reporting before using the figures.” That makes clear that your worksheet organizes evidence rather than deciding the final tax treatment.

Distinguish a deduction from a refund

The $8,000 and $4,000 figures are assumed deductible interest in a simplified example, not checks from the IRS or guaranteed tax savings. Do not promise to reimburse a co-owner based on those amounts without understanding the actual return and your own agreement.

Before filing, ask the preparer to confirm that the correct tax year and reporting method were used and that any required explanation is included. Review the final numbers rather than assuming the imported Form 1098 automatically created the intended allocation.

Keep the final worksheet with the records supporting it. If a corrected form later arrives, compare it with the original and ask whether either return needs attention; do not silently replace the old document and lose the history.

Sources checked November 4, 2026. This is general federal tax education, not an individual deduction determination.