Interest on a boat loan is deductible as home mortgage interest when three conditions line up: the boat has sleeping, cooking, and toilet facilities, the loan is secured by the vessel itself, and your combined acquisition debt on your primary home and the boat stays within $750,000. Miss any one of those and the boat loan interest tax deduction is off the table, leaving the interest as ordinary personal debt with no tax benefit. You also have to itemize on Schedule A for the deduction to produce any real savings.
When a Boat Counts as a Second Home
IRS Publication 936 treats a boat as a “home” if it has sleeping, cooking, and toilet facilities.1Internal Revenue Service. Publication 936 – Home Mortgage Interest Deduction All three, not two of three. A center console with a berth but no galley and no head doesn’t make the cut. A cruiser with a V-berth, a small stove, and a marine toilet does.
The boat also has to be one of your two designated residences for the year. The tax code lets you deduct mortgage interest on your principal residence plus one other residence you select.2Office of the Law Revision Counsel. 26 USC 163 – Interest If you already own a house and a vacation condo, you’d have to pick between the condo and the boat. There’s no third slot.
You don’t need to prove you slept aboard a minimum number of nights. When a dwelling isn’t rented out at all during the year, the statute treats it as a residence automatically.2Office of the Law Revision Counsel. 26 USC 163 – Interest The personal-use test only appears once you introduce rental days.
The Loan Has to Be Secured by the Boat
Only “acquisition indebtedness” qualifies, and the tax code defines that as debt used to buy, build, or substantially improve a qualified residence and secured by that residence.2Office of the Law Revision Counsel. 26 USC 163 – Interest For a boat, that means a marine lender’s lien recorded against the vessel’s title under state law.
An unsecured personal loan used to buy the boat doesn’t work, even if the boat itself checks every facilities box. A credit card purchase doesn’t work. A home equity draw against your house is a separate loan against your house, not against the boat, so it doesn’t qualify under this route either. The security interest has to be in the vessel.
The $750,000 Debt Ceiling
For loans taken out after December 15, 2017, deductible mortgage interest is capped at the interest on up to $750,000 of combined acquisition debt across both homes. Married filing separately, the cap is $375,000.2Office of the Law Revision Counsel. 26 USC 163 – Interest These limits were temporary under the 2017 tax law and are now permanent.3Congress.gov. Tax Provisions in H.R. 1, the One Big Beautiful Bill Act
The ceiling is a combined ceiling, and that’s where boat owners get surprised. Suppose you carry a $600,000 mortgage on the house and add a $200,000 boat loan. Combined acquisition debt is $800,000, which is $50,000 over the limit. Interest on roughly 6.25% of the total (the excess divided by the total) is non-deductible; the rest still qualifies. The math is a straight proration.
If your home mortgage predates December 16, 2017, the older $1 million limit still applies to that legacy debt, but new debt (including a boat loan taken out today) sits under the newer $750,000 rule and reduces the room available under it.1Internal Revenue Service. Publication 936 – Home Mortgage Interest Deduction
Itemizing Has to Beat the Standard Deduction
Boat loan interest only appears on your return if you itemize on Schedule A.4Internal Revenue Service. Instructions for Schedule A (Form 1040) For 2026, the standard deduction is $32,200 for married filing jointly, $16,100 for single and married filing separately, and $24,150 for head of household.5Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
Your itemized total, adding boat and home mortgage interest, state and local taxes, and charitable contributions, has to clear that number for itemizing to pay off. A married couple with $18,000 in combined mortgage interest, $10,000 in property taxes, and $5,000 in charitable gifts totals $33,000, barely above the $32,200 floor. The marginal benefit from the boat interest alone is modest in that situation. Plenty of boat owners with smaller loans find the standard deduction wins, and the boat interest deduction goes unused.
What Changes If You Rent the Boat Out
Renting the boat doesn’t automatically kill the second-home status, but it introduces a personal-use test. When you rent at fair market rates, you also have to use the boat personally for more than the greater of 14 days or 10% of the total rental days for it to remain your residence.6Office of the Law Revision Counsel. 26 USC 280A – Disallowance of Certain Expenses in Connection With Business Use of Home, Rental of Vacation Homes, Etc. Below that threshold, the boat is treated as pure rental property and the Schedule A mortgage interest deduction disappears.
Rental activity also brings passive activity loss rules into play, so any net loss on the rental side generally can’t offset your wages.7Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited There is one clean win: if you rent the boat fewer than 15 days during the year, the rental income isn’t taxable at all, and you keep the full mortgage interest deduction as long as the boat still meets second-home requirements.8Internal Revenue Service. Topic No. 415, Renting Residential and Vacation Property
Refinancing and Cash-Out
Refinancing the boat loan at the same balance keeps the interest fully deductible. The tax code treats refinanced acquisition debt as still being acquisition debt so long as the new loan doesn’t exceed the remaining balance of the old one.2Office of the Law Revision Counsel. 26 USC 163 – Interest
Cash-out is where it breaks. Refinance a $150,000 boat loan into a $200,000 loan and use the extra $50,000 for anything other than buying, building, or substantially improving the boat, and interest on that $50,000 slice is not deductible. Home equity debt used for unrelated purposes lost its deduction under the 2017 law, and that restriction is now permanent.1Internal Revenue Service. Publication 936 – Home Mortgage Interest Deduction
Business Use as a Separate Route
If the boat is used in a genuine business (a charter operation, for example), the loan interest becomes a business expense on Schedule C rather than a mortgage interest item on Schedule A.9Internal Revenue Service. Instructions for Schedule C (Form 1040) Two advantages come with that path: the $750,000 acquisition debt cap doesn’t apply, and you don’t have to itemize to benefit.
Mixed-use boats require allocation. A charter used commercially 200 days and personally 50 days produces an 80% business share. You’d deduct 80% of the interest on Schedule C and, if the boat qualifies as a second home and you itemize, the remaining 20% on Schedule A. Dated logbooks documenting each use support the split.
One warning applies to charter operations that lose money year after year while the owner uses the boat on weekends. The IRS can reclassify the activity as a hobby and disallow the business deductions, including interest, under section 183.10Office of the Law Revision Counsel. 26 USC 183 – Activities Not Engaged in for Profit A safe harbor exists: three profitable years out of any five consecutive years creates a presumption that the activity is a real business.
Sales Tax in the Purchase Year
Separate from the interest itself, sales tax paid when you buy the boat can be deductible on Schedule A. You choose between deducting state and local income taxes or state and local general sales taxes for the year, whichever gives you more.11Internal Revenue Service. Topic No. 503, Deductible Taxes In the year of a major purchase, the sales tax number often wins.
Both sit under the SALT cap, which is $40,000 for most filers ($20,000 married filing separately) subject to an income-based phase-down.11Internal Revenue Service. Topic No. 503, Deductible Taxes Even with the cap, the sales tax election can be meaningful. State vessel sales tax rates typically run from 4% to 9%, so a $400,000 boat could produce $16,000 to $36,000 in deductible sales tax for that year.
Reporting the Interest Without a Form 1098
Lenders generally issue Form 1098 for mortgage interest of $600 or more,12Internal Revenue Service. About Form 1098, Mortgage Interest Statement but boat lenders often don’t, because the 1098 requirement applies to loans secured by real property and a boat is personal property. You can still take the deduction. You just have to supply the information yourself.
Request a year-end statement from the lender showing interest paid, principal paid, and outstanding balance. Report the interest on Schedule A under home mortgage interest, and where no 1098 was issued, enter the lender’s name, address, and taxpayer identification number along with the interest amount.4Internal Revenue Service. Instructions for Schedule A (Form 1040)
Hold on to records that prove the boat qualifies. Dated photos of the sleeping area, galley, and head are the easiest evidence. Keep the loan documents showing the security interest, the state registration or Coast Guard documentation, and any purchase survey. If you rent the boat at all, keep a day-by-day usage log. In an audit, the IRS will want to see that the boat meets the second-home facilities test, that the loan is secured by the vessel, and that your combined acquisition debt fits under the statutory cap.