HELOC Tax Deduction: When Interest Is Deductible (and When It Isn't) in 2026

Before 2017, HELOC interest was broadly deductible regardless of how the proceeds were used. The Tax Cuts and Jobs Act changed that rule sharply. Today, the deductibility of your HELOC interest depends entirely on what you spent the money on — and the IRS audits this distinction more carefully than most homeowners realize.

The current rule, in one sentence

HELOC interest is deductible only when the loan proceeds are used to "buy, build, or substantially improve" the home that secures the loan, and only up to the overall mortgage interest deduction limit of $750,000 in combined acquisition and home-improvement debt for the home.

Both halves of that sentence matter. The use test determines whether any deduction is available. The dollar cap determines how much of your interest you can deduct.

The use test in plain English

The IRS uses three categories of qualifying use:

Buying the home. Using a HELOC as part of the original purchase financing. This is rare in 2026 because most home purchases are financed with a single first mortgage, but it does happen — for example, when a borrower takes out a piggyback HELOC to avoid PMI on a high-LTV purchase.

Building the home. Using HELOC proceeds for new construction or major additions. A homeowner who pulls $200,000 from a HELOC to fund a 1,500-square-foot addition is using the proceeds for "building."

Substantially improving the home. This is where the audit risk lives. The improvement must be substantial — meaning it adds value to the home, prolongs its useful life, or adapts it to new uses. Routine maintenance does not qualify.

Examples of substantial improvements:

• Kitchen renovation that changes the layout or upgrades major appliances
• Bathroom renovation
• Roof replacement
• HVAC system replacement
• Adding a deck, patio, or pool
• Finishing a basement
• Replacing windows
• Adding insulation or solar panels

Examples of non-qualifying improvements:

• Painting the exterior or interior (unless part of a larger renovation)
• Replacing carpet
• Repairing a leaky faucet
• General lawn care
• Cosmetic changes that don't affect value or use

The non-qualifying uses that catch borrowers

The most common HELOC uses that do not qualify for the interest deduction:

Debt consolidation. Using a HELOC to pay off credit cards, student loans, or auto loans is not a qualifying use. The interest is not deductible regardless of how much you save in net interest cost.

College tuition. Pulling HELOC funds to pay for a child's college education does not qualify. The interest is not deductible, even though the use is generally considered prudent.

Medical bills. Paying medical expenses with HELOC proceeds does not qualify, regardless of the medical necessity.

Vacations or large purchases. Using HELOC funds for travel, weddings, vehicles, or other consumer goods does not qualify.

Investment in another property. Using HELOC proceeds from your primary residence to invest in a rental property does not qualify under the home-improvement rules. (The interest may still be deductible as investment interest, but under different and stricter rules.)

Business uses. Using HELOC funds to start or grow a business does not qualify under the home-improvement rules. The interest may still be deductible as a business expense, but the deduction flows through your business return rather than your personal Schedule A.

The dollar cap

Even when the use qualifies, the deduction is capped. The total of your acquisition debt (your first mortgage used to buy the home) plus your home-improvement debt (your HELOC used for substantial improvements) cannot exceed $750,000 for loans originated after 2017.

Loans grandfathered from before December 16, 2017 retain the older $1 million cap, but few HELOC borrowers fall in this group given the typical line lifecycle.

Worked example: A homeowner has a $700,000 first mortgage on a home worth $900,000. They take a HELOC and use $100,000 for a kitchen renovation. Their combined acquisition + improvement debt is $800,000. They can deduct the interest on the first $750,000 of combined debt — meaning the interest on the last $50,000 of HELOC borrowing is not deductible.

For most middle-income homeowners with home values under $1 million, this cap doesn't bind. For homeowners in higher-priced markets or with higher mortgage balances, the cap can disallow part of the HELOC interest deduction.

The mixed-use complication

What happens when you use part of a HELOC draw for a qualifying purpose and part for a non-qualifying purpose? The IRS requires you to allocate the interest proportionally.

Example: You draw $80,000 from a HELOC. You use $50,000 for a kitchen renovation (qualifying) and $30,000 to pay off credit cards (non-qualifying). The IRS requires you to deduct only 62.5% of the interest you pay on that draw — the proportion attributable to the qualifying use.

This allocation continues over the life of the balance. As you pay down the HELOC, you must track which portion of the remaining balance is qualifying vs. non-qualifying. Most homeowners do this by allocating payments to the non-qualifying portion first, which simplifies the tracking and maximizes the deduction over time.

The mixed-use complication is one of the strongest arguments for keeping your HELOC use clean — either fully qualifying or fully non-qualifying — rather than mixing.

Documentation that protects you in an audit

If the IRS audits your HELOC interest deduction, you'll need to demonstrate that the proceeds were used for qualifying purposes. The documentation that protects you:

Contractor invoices and receipts for the improvement work, dated within a reasonable window of the HELOC draw.

Bank statements showing the HELOC funds flowing to the contractor or supplier rather than to general personal accounts.

Permits and inspection records for substantial improvements that required them.

Photographs of the before-and-after state of the improvement.

The cleanest documentation pattern is a HELOC draw that goes directly to a contractor, with a contractor invoice that matches the draw amount, accompanied by permits if required.

The riskiest documentation pattern is a HELOC draw that goes to a personal checking account, where the funds mingle with other money before being spent. Audit trails get murky in this scenario, and the IRS examiner has discretion to deny the deduction.

Our recommendation

If you're using HELOC funds for home improvement, document obsessively from the start. Keep contractor invoices, take photographs of the work, retain permits, and direct HELOC draws to contractor accounts when possible.

If you're using HELOC funds for non-qualifying purposes, don't claim the deduction. The interest savings on a wrongly-claimed deduction are small compared to the penalties and interest the IRS can assess on amended returns.

If you're using HELOC funds for mixed purposes, talk to a tax professional. The allocation rules are complex enough that the few hundred dollars in fees for a clean tax return often pay for themselves in the deductions you can defensibly claim.

This article is general information, not personalized financial advice. Rates, fees, and tax treatment may vary by lender and individual circumstances. Consult a qualified professional before making large financial decisions.