Interest Tracing Rules: Rental Refinance & HELOC Examples

Interest generally follows how borrowed money is spent, not which property secures the loan. A cash-out refinance used for personal spending does not become rental interest just because a rental property is collateral. A borrowing used for a rental purchase can be allocated to that rental, subject to the applicable deduction rules.

Trace the Expenditure Before Claiming a Deduction

Treasury Regulation 1.163-8T provides the debt allocation framework. Separate business, rental, investment and personal uses, then apply the rules for each category. Allocation to a rental does not by itself establish the current-year deduction: capitalization, passive-activity restrictions, business-interest limitations and other rules may apply.

Home-secured debt requires additional care because qualified residence interest rules and an election to treat debt as not secured by the home may affect treatment. A HELOC used for a rental purchase should not simply be placed on Schedule A or Schedule E based only on its label. Review the loan and use of funds with the return preparer.

Mixed Accounts: Ordering Rules Do Not Expire After 15 Days

The default rules generally treat expenditures from an account as funded by debt proceeds before unborrowed amounts, with borrowed amounts ordered by deposit. They continue while debt proceeds remain allocated to the account; they are not merely a 15-day rule. Transfers between accounts need their own trail.

For example, a borrower deposits $100,000 in refinance proceeds, spends $20,000 on a personal vacation, then pays $80,000 toward a rental purchase. Without another permitted allocation choice and supporting facts, the later rental payment does not retroactively turn the personal spending into rental use. Keep complete statements, not only the final closing wire.

The 30-Day Allocation Rule

Treasury Regulation 1.163-15 allows expenditures from any account of the taxpayer, or cash, within 30 days before or after receipt or deposit of debt proceeds to be treated as funded by those proceeds, to the extent available. This is the current authority for the broader rule; it is not the 15-day provision in Regulation 1.163-8T(c)(4)(iii)(B).

An acquisition paid on March 3 and borrowing deposited on March 20 fall within that timing window. The preparer must still confirm the taxpayer, eligible expenditure, amount and allocation, and ensure the funds were not counted twice. The rule provides allocation flexibility, not permission to relabel an undocumented personal purchase.

Worked Example: Split Rental and Home Improvement Use

Assume a $220,000 HELOC is fully drawn at the beginning of the year, bears a fixed 8.25% rate, and remains outstanding without repayment. The owner directly uses $185,000 for a rental down payment and $35,000 for work on the home securing the HELOC. Ignore fees for this illustration.

Total annual interest: $220,000 × 8.25% = $18,150.
Rental-use allocation: $185,000 × 8.25% = $15,262.50.
Home-improvement allocation: $35,000 × 8.25% = $2,887.50.

The allocations sum to the total; do not round the rental-use percentage to 84% before calculating interest. Whether and where either portion is deductible requires a separate review of qualified residence interest, any applicable election, rental limitations and the actual work performed. With repayments, changing rates or later draws, use the actual dated balances rather than this full-year simplification.

Refinancing, Repayments and Changes in Use

Replacement debt used to repay existing borrowing generally carries forward the allocation of the debt repaid; additional cash-out proceeds require a new trace. Mixed-use repayments have ordering rules. Selling a financed asset, converting a rental to personal use or reinvesting sale proceeds may require reallocation. Do not assume the original percentage lasts forever.

Build a Loan-by-Loan Tracing File

List each lender, loan, draw date, amount and opening allocation.
Match the draw to account deposits and each transfer or payment.
Identify the recipient, property, business or personal purpose and supporting closing statement or invoice.
Record any 30-day allocation choice and reconcile it to the remaining proceeds.
Reconcile interest, principal repayments and later draws to year-end statements.
Carry the closing allocation to the next year's workpapers.

For broader context, read IRS Publication 550, Allocation of Interest Expense, and the home mortgage interest guidance in Publication 936. If the borrowing belongs to a partnership or funds an owner distribution, obtain entity-level analysis rather than assuming the individual example controls.

Use the rental cash-out refinance guide for transaction context, then review rental tax preparation or partnership return preparation for the appropriate filing work.

Frequently Asked Questions

Is interest deductible because the loan is secured by a rental property?

Not by itself. Interest is generally allocated by use of the borrowed funds. Collateral also matters for special rules such as qualified residence interest, so tracing and deduction eligibility must both be reviewed.

Can I deduct HELOC interest used to buy a rental?

Potentially. Trace the borrowing to the rental purchase and review the rules for home-secured debt, including whether an election is appropriate. Rental allocation does not override capitalization, passive-loss or other applicable limits.

What happens if I mix loan proceeds with other money?

Apply the account ordering rules and any available allocation choice to the actual dated transactions. A separate account makes the trace easier to document but is not a guarantee of deductibility.

Is there timing flexibility in tracing?

Treasury Regulation 1.163-15 permits allocation to qualifying expenditures from any taxpayer account or cash within 30 days before or after receipt or deposit, up to the proceeds allocated. Keep a consistent schedule and do not allocate the same proceeds twice.

How do I trace interest on a portfolio line of credit?

Track each draw, payment, use and later reallocation. Tie the schedule to bank records, closing statements and invoices; a list of properties pledged as collateral does not establish how each draw was spent.

Interest Tracing Rules: Why Your Loan Security Does Not Determine Deductibility