There's a tax trap buried in a cash-out refinance that almost nobody explains to you before you sign — and it can quietly cost you thousands at tax time. It's not about your rate. It's not about your payment. It's about whether the interest on that loan is even deductible anymore. And the honest answer is: some of it probably isn't — and the person handing you the check has almost no reason to walk you through why.
By the end of this, you'll understand the difference between purchase debt and home equity debt, how a cash-out refinance can quietly convert one into the other, and the one move that saves your deduction if you plan for it in advance. This mistake is one of the most common I've seen, and it usually gets discovered by a tax preparer months after the money's already been spent.
What "purchase debt" actually means
Start with the original loan you use to actually buy a home. In the tax world, that's called acquisition indebtedness — most people just call it purchase debt. It's simple: you borrowed the money specifically to buy, build, or substantially improve the home that's securing the loan. Because of that direct connection between the money and the house, the interest on that loan is generally deductible, up to the loan limits the tax code allows.
That's the loan almost everyone pictures when they think about "the mortgage interest write-off." Money went in to buy the house, and the interest on it gets a tax break. Clean and intuitive. The trouble starts when a later transaction breaks that clean connection — and a cash-out refinance is exactly the kind of transaction that can.
How a cash-out refinance changes the tax character
Say a few years go by, your home's worth more, and you do a cash-out refinance to pull some of that equity out as cash. The new loan replaces your old one, and it grows to include the cash you took out. Same house, bigger loan, one monthly payment. In your head, it's all just "the mortgage" now.
But here's the part nobody tells you: the moment that cash leaves the house for a purpose that isn't tied to the home, the tax character of that portion of the debt changes. It stops being purchase debt. It becomes home equity debt — and the interest on that piece is generally not deductible anymore. Your monthly statement still says "mortgage." The IRS doesn't care what the statement says. It cares where the money went.
| Purchase debt (acquisition) | Home equity debt (cashed out for other uses) | |
|---|---|---|
| What it is | Money borrowed to buy, build, or substantially improve the home securing the loan | Cash pulled from your equity and used for something unrelated to that home |
| Examples | Original purchase loan; a rate-and-term refi; cash-out spent on a room addition or new roof | Cash-out used to pay off a car or boat, consolidate debt, cover tuition, or take a vacation |
| Interest deductible? | Generally yes, up to tax-code loan limits | Generally no — regardless of how it's packaged into the loan |
The one exception that can save your deduction
There's one major exception, and it's the thing that can save you. If you take the cash out and use it to build, buy, or substantially improve the home that's securing the loan — a room addition, a new roof, a major renovation — that portion can still qualify as acquisition debt, and the interest on it can still be deductible.
The key phrase is substantially improve. Regular maintenance and small repairs typically don't count. Repainting a bedroom or fixing a leaky faucet is upkeep, not a capital improvement. It has to be a real improvement to the property — the kind of thing that adds value, extends the home's life, or adapts it to a new use. Money that goes back into the house in that way has a real shot at staying deductible. Money that leaves the house does not.
Why loan officers don't explain this
Here's the bank-versus-you angle, because this is exactly where people get hurt. I've been in this business since 2007, before loan officers even needed a license, and I'll tell you plainly: almost nobody explains this distinction when they're pitching a cash-out refinance. Why would they? Their job is to get the loan funded — not to walk you through IRS code.
So the borrower closes, gets a check, and in their head that money is just part of their mortgage now. Same house, same loan, same tax treatment as always. Nobody said otherwise, so they assume nothing changed. That silence is the trap.
Purchase debt is clean water — the tax code lets it through. When you pour a car loan into your mortgage, you didn't purify it; you just poured dirty water into a bigger bucket labeled "mortgage." The label on the bucket doesn't change what's inside. The IRS tests the water, not the bucket — so that portion stays non-deductible no matter how nicely it's packaged into your house payment.
The car-and-boat mistake I see over and over
Here's the version of this I watch happen again and again. People take the cash and pay off a car loan or a boat loan with it. In their mind, they just did something smart — they wiped out high-interest debt. And they walk away believing two things that don't both hold up.
First, they think the car or boat is now free and clear. True — it is. But second, they think the interest they're now paying on that same chunk of money, rolled into the mortgage, is still fully tax deductible simply because it's part of the house payment. It is not. You didn't make that debt deductible by moving it into your mortgage. You just changed who you owe and what the interest rate is. Dragging a car loan into your house payment does not turn it into home acquisition debt — even though your monthly statement now says "mortgage" on it.
The two-bucket move before you close
So here's the move, and it's simple. Before you do a cash-out refinance, sit down and separate your reasons into two buckets:
- Bucket one — money going back into the house: a renovation, an addition, a major repair that counts as a real improvement. That piece has a real shot at staying deductible.
- Bucket two — everything else: vehicles, debt consolidation, tuition, a vacation, whatever it is. That piece is very likely not deductible, no matter how it's packaged into your new loan.
Knowing which bucket your dollars are landing in before you close is the whole game. Do it after, and you're just handing your tax preparer a problem to discover next spring.
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Educational content only — not financial, mortgage, legal, or tax advice, and not a loan offer or solicitation. Every situation is different; the rules around mortgage interest deductibility are technical and change over time. Consult a licensed tax professional before you rely on any deduction. Timothy George is the founder of Infinity Financial Mortgage Corporation and has been in the mortgage business since 2007; he is not a currently-licensed loan originator and does not originate loans. The rules on the home mortgage interest deduction, acquisition indebtedness, and home equity debt are set out in IRS Publication 936 (Home Mortgage Interest Deduction); general consumer information on cash-out refinancing and home equity is available from the Consumer Financial Protection Bureau (CFPB). Tax rules, loan limits, and eligibility change over time and vary by situation — confirm the current rules and your specific facts with a licensed tax professional before you act.