Is Business Interest Expense Tax Deductible? Limits & Tracing

Yes, business interest expense is tax deductible under federal law. When your business borrows money and uses it for business purposes, the interest you pay on that debt generally reduces your taxable income.1Office of the Law Revision Counsel. 26 USC 163 – Interest The catch is that larger businesses face a cap tied to 30% of adjusted taxable income, some interest has to be capitalized rather than written off in the year it’s paid, and how you use the borrowed money determines whether the interest counts as business interest at all.

What Has to Be True Before You Can Deduct It

Three conditions apply to every business interest deduction. You, or your business entity, must be legally obligated to repay the debt; you can’t deduct interest on someone else’s loan just because your business benefited from the money. A genuine debtor-creditor relationship has to exist, because the IRS will look hard at arrangements that resemble disguised gifts or equity investments. And the borrowed money must go to a legitimate business purpose. Interest on personal borrowing doesn’t qualify, even if you happen to own a business.1Office of the Law Revision Counsel. 26 USC 163 – Interest If a single loan covers both business and personal expenses, only the business share of the interest comes off your taxes.

When you claim the deduction depends on your accounting method. Cash-basis taxpayers deduct interest in the year they actually pay it. Accrual-basis taxpayers deduct it in the year the obligation accrues, meaning the amount is fixed and determinable, regardless of when the money changes hands.

Types of Borrowing That Produce Deductible Interest

Most ordinary business borrowing generates deductible interest:

  • Equipment and vehicle loans covering machinery, delivery trucks, computers, or other tangible assets.
  • Commercial mortgages on warehouses, offices, retail space, or other business real estate.
  • Business credit cards and lines of credit used for inventory, supplies, marketing, or similar expenses.
  • Working capital loans covering payroll, rent, utilities, and other operating costs.

What matters is how you spend the money, not what the loan is called. A personal credit card doesn’t become deductible because you own a business, and a business card charge for a family vacation isn’t deductible either.

When Interest Has to Be Capitalized Instead

Interest incurred during the construction or production of certain property can’t be written off in the year you pay it. Under the uniform capitalization rules, that interest gets added to the cost of the property and recovered over time through depreciation.2Office of the Law Revision Counsel. 26 USC 263A – Capitalization and Inclusion in Inventory Costs of Certain Expenses The rule covers real property you build and other assets with a long useful life, a production period longer than two years, or a production period longer than one year with a cost above $1 million. In practical terms, if you take out a construction loan for a new warehouse, the interest paid during construction folds into the building’s basis rather than becoming an immediate write-off.

Prepaid Interest

If you pay interest in advance, cash-basis taxpayers can’t deduct the whole amount in the year of payment. The prepaid portion is allocated to the tax periods it actually covers.3Office of the Law Revision Counsel. 26 USC 461 – General Rule for Taxable Year of Deduction Prepay 18 months of interest in December, and only December’s share is deductible that year.

Loan Points and Origination Fees

Points and origination fees on a commercial mortgage aren’t a lump-sum write-off in the year you close. They get added to the property’s basis and recovered through depreciation. This is less favorable than the treatment for points on a primary personal residence.

Interest Tracing When You Mix Funds

If loan proceeds land in an account that already holds personal or other money, interest tracing rules decide which expenses the borrowed money actually paid for, and therefore how much of the interest counts as business interest.4eCFR. 26 CFR 1.163-8T – Allocation of Interest Expense Among Expenditures The classification of the interest follows the use of the loan proceeds, not the purpose of the loan on paper.

The general ordering rule treats loan proceeds deposited into an account as spent before any unborrowed funds already sitting there. There’s also a shortcut: if you make a business expenditure from the account within 15 days of depositing the loan proceeds, you can treat that expenditure as coming from the borrowed funds regardless of the ordering rule.4eCFR. 26 CFR 1.163-8T – Allocation of Interest Expense Among Expenditures The cleanest approach is to run loan proceeds through a dedicated business account and spend them on identifiable business expenses, which avoids tracing disputes altogether.

The 30% Cap for Larger Businesses

Section 163(j) limits how much interest a larger business can deduct in a single tax year. The cap equals:1Office of the Law Revision Counsel. 26 USC 163 – Interest

  • Your business interest income for the year, plus
  • 30% of your adjusted taxable income (ATI), plus
  • Your floor plan financing interest, meaning debt used to finance motor vehicles or farm equipment held for sale or lease.

For tax years beginning after December 31, 2024, which includes 2026, the One, Big, Beautiful Bill restored a more favorable ATI calculation. Businesses can add back depreciation, amortization, and depletion when computing ATI, which produces a higher number and a larger allowable deduction.5Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense From 2022 through 2024, those add-backs weren’t allowed, which made the cap significantly tighter for capital-intensive businesses.

The Small Business Exemption

Many businesses are exempt from the cap entirely. For tax years beginning in 2026, a business with average annual gross receipts of $32 million or less over the preceding three tax years isn’t subject to the 163(j) limitation.6Internal Revenue Service. Revenue Procedure 2025-32 The threshold adjusts annually for inflation. It was $31 million for 2025 and $30 million for 2024.5Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense Businesses below the threshold deduct their full interest expense without running the 30% calculation.

Carryforward for Disallowed Interest

Business interest that exceeds the cap in a given year isn’t lost. It carries forward to the next tax year and can be deducted then, subject to that year’s limit, with no stated expiration.5Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense Partnerships apply the cap at the partnership level and allocate disallowed interest to partners as “excess business interest expense,” which each partner carries forward and can deduct only when the same partnership allocates excess taxable income or excess business interest income to them. S-corporations keep the disallowed interest at the corporate level rather than passing it through to shareholders.

Electing Out for Real Estate and Farming

Certain real property trades or businesses and farming businesses can elect out of the 163(j) cap entirely, regardless of size. The trade-off: the business has to depreciate its nonresidential real property, residential rental property, and qualified improvement property under the Alternative Depreciation System, which uses longer recovery periods, and it loses bonus depreciation on those assets.5Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense The election is irrevocable, so it’s worth modeling out the value of unlimited interest deductions against slower depreciation before making the call.

Interest Paid to a Related Party

Paying interest to a family member or an entity you control triggers a specific timing rule. If you owe interest to a related party who uses the cash method of accounting, you can’t deduct that interest until the related party actually reports it as income.7Office of the Law Revision Counsel. 26 USC 267 – Losses, Expenses, and Interest With Respect to Transactions Between Related Taxpayers This stops an accrual-basis business from claiming a deduction in one year while the cash-basis lender defers the income.

The rule reaches a broad set of relationships, including siblings, spouse, parents, grandparents, and children or grandchildren; an individual and a corporation where the individual owns more than 50% of the stock; two corporations or a corporation and a partnership sharing more than 50% common ownership; and trusts in relation to their grantors, beneficiaries, or related corporations.

Timing isn’t the only risk. The IRS can reclassify a related-party “loan” as an equity investment if it lacks genuine debt characteristics, looking at whether the loan has a fixed maturity date, whether the lender can enforce repayment, whether the borrower is thinly capitalized, and whether the lender and the borrower’s shareholders are the same people. If the instrument is treated as equity, the interest payments become non-deductible distributions.

Reporting the Deduction and Keeping Records

Where you report business interest depends on your entity:

Any business over the $32 million gross receipts threshold, or one with a disallowed interest carryforward or excess business interest expense from a partnership, also files Form 8990 to calculate the allowable deduction and track carryforward amounts.12Internal Revenue Service. Instructions for Form 8990 – Limitation on Business Interest Expense Under Section 163(j) Small businesses that meet the gross receipts test and have no partnership carryforward are excused from filing. Consolidated corporate groups file one Form 8990 for the group.

The records that support the deduction should include the loan agreement or promissory note establishing the debt, rate, and repayment terms; an amortization schedule showing the split between principal and interest in each payment; Form 1098, which lenders provide when they receive $600 or more in mortgage interest during the year;13Internal Revenue Service. About Form 1098 – Mortgage Interest Statement and bank statements or canceled checks for private loans, lines of credit, or any arrangement without a 1098. If you’re relying on the interest tracing rules for a commingled account, keep records showing when the loan proceeds landed and when business expenditures went out, because the 15-day window only helps if you can document both.

What It Costs to Overstate the Deduction

Claiming interest you shouldn’t, whether through misallocation, ignoring the 163(j) cap, or treating personal interest as a business expense, comes with more than just repaying the tax. If the error causes a substantial understatement of your tax liability, the IRS charges a 20% accuracy-related penalty on the underpayment.14Internal Revenue Service. Accuracy-Related Penalty For individuals, “substantial” means the tax was understated by the greater of 10% of the correct tax or $5,000.

Interest on the underpayment runs from the date the tax was originally due. For the first quarter of 2026, the federal underpayment rate is 7%, rising to 9% for large corporate underpayments, and the rate is reset quarterly.15Internal Revenue Service. Revenue Ruling 2025-22 – Determination of Rate of Interest Filing an amended return as soon as you spot an error limits the interest that accumulates and can help support a reasonable-cause argument against the penalty itself.