Mortgage Interest
& Tracing Rules
It's usually your biggest deduction. But if you used that HELOC for a boat, deducting the interest is tax fraud. Here's how to get it right.
A guide by Taxstra Tax & Accounting — CPA-led tax strategy for business owners
Quick Answer
Mortgage interest on rental property is deductible on Schedule E Line 12 — but unlike your primary home, there is no $750,000 debt cap. The key rule for rentals is the Tracing Rule: deductibility follows how the borrowed money was used, not which property secures the loan. A HELOC on your home used to buy a rental generates deductible Schedule E interest. A cash-out refi on your rental used to buy a vacation does not.
The Tracing Rule
The IRS ignores which property secures the loan. They follow the cash.
Mortgage interest is the lifeblood of real estate investing leverage. For most landlords, Line 12 completely offsets rental income, often resulting in a "paper loss" that shelters cash flow from taxes. However, the rules for rental interest differ significantly from personal home interest — and the Tracing Rule under Temp. Reg. § 1.163-8T is what trips investors up most often. For a complete deep-dive on deducting HELOC interest on a rental property, see our full HELOC guide.
| Scenario | Tax Treatment | Reason |
|---|---|---|
| HELOC on personal home → funds used to buy rental | Deductible on Schedule E (rental) | ✅ Follows the cash to rental |
| Cash-out refi on rental → funds used to buy a boat | NOT deductible (personal use) | ❌ Cash went to personal asset |
| Purchase mortgage on rental property | Deductible on Schedule E | ✅ Straightforward |
| HELOC partially for rental, partially personal | Only rental portion deductible | ⚠️ Must allocate by use of funds |
Points & Amortization
"Points" (loan origination fees) are considered Prepaid Interest. Unlike a primary residence where you might deduct points immediately, rental points must generally be amortized over the life of the loan.
How to Calculate Annual Amortization
Don't Deduct Principal!
A very common mistake among new landlords is deducting the entire mortgage payment. Only the interest portion of each payment is deductible. Principal payments reduce your loan balance — they are not an expense. Your lender's amortization schedule shows the split for each payment.
Monthly Payment Breakdown — $2,000/month Example
Audit Defense Checklist
Form 1098 is the starting point, not the ending point.
Form 1098
The bank sends this if you paid more than $600 in interest. Match Line 12 strictly to this form IF the loan is solely for the rental.
Closing Disclosure (CD)
Critical for the first year of a purchase or refinance. Proves Points, Prepaid Interest, and the exact loan amount.
Improvement Ledgers (Tracing)
If you used a HELOC, keep a spreadsheet showing exactly which receipts were paid with those specific loan funds.
Sources & Citations
- • IRS Publication 936 (Home Mortgage Interest Deduction)
- • Temp. Reg. § 1.163-8T (Tracing Rules)
- • IRS Publication 527 (Residential Rental Property)
Frequently Asked Questions
Next Steps
Filing it yourself is fine — optimizing it is where the money is
Getting the form right keeps you out of trouble. The strategies below are what actually lower the bill.
HELOC on an Investment Property
Deducting HELOC interest on a rental comes down to the tracing rules. The full guide on getting every dollar of HELOC interest where it belongs.
Cost Segregation Study
Interest shelters some rental income — accelerated depreciation can wipe out far more. How a cost seg study front-loads 27.5 years of deductions.
Leveraged portfolio? The interest deduction is only the start.
Free 30-minute call with a Taxstra CPA — no pressure, just the math for your situation.
HELOC or Complex Financing Structure?
Taxstra CPAs untangle tracing rules for HELOCs, cash-out refis, and private loans — ensuring every dollar of interest that should be deductible actually is. Book a free 30-min call.
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Educational Disclaimer
This content is for educational purposes only and does not constitute individualized tax advice. Consult a licensed CPA before making tax decisions. Updated for the 2025 tax year.
