Tax Deductions on Business Loan Interest: What You Can Write Off in 2026

Tax Deductions on Business Loan Interest: What You Can Write Off in 2026

One of the most overlooked benefits of business financing is the tax deductibility of loan interest. For many small business owners, the ability to deduct interest payments from taxable income meaningfully reduces the true cost of borrowing. Yet according to the National Small Business Association, nearly 40 percent of small business owners are unaware of or fail to claim all the deductions available to them.

This guide explains exactly which types of business loan interest are deductible, how to calculate and claim the deduction, and the common mistakes that can trigger an audit or result in a disallowed claim.

The Basic Rule: Business Loan Interest Is Deductible

The IRS allows businesses to deduct interest paid on loans used for legitimate business purposes. This applies to a wide range of financing products including term loans, SBA loans, business lines of credit, equipment financing, and commercial mortgages. The key requirement is that the borrowed funds must be used for business operations, not personal expenses.

If you take out a $100,000 business loan at 10 percent APR and pay $10,000 in interest during the tax year, that $10,000 is deductible as a business expense on your tax return. At a 25 percent effective tax rate, the deduction saves you $2,500, reducing your effective interest rate from 10 percent to 7.5 percent.

Which Types of Interest Are Deductible?

Term Loan Interest

Interest on fixed-term business loans, whether from banks, credit unions, or online lenders, is fully deductible as a business expense. This includes both fixed-rate and variable-rate loans.

SBA Loan Interest

Interest on SBA 7(a) loans, SBA 504 loans, and SBA microloans is deductible. The SBA guarantee fee, which is paid at closing, is also deductible as a financing cost.

Line of Credit Interest

Interest charges on a business line of credit are deductible when the drawn funds are used for business purposes. Since you only pay interest on the amount drawn, you deduct only the interest actually incurred.

Equipment Financing Interest

If you finance equipment through an installment loan, the interest portion of each payment is deductible. If you lease equipment under a capital lease, the interest component is also deductible. Additionally, the equipment itself may qualify for Section 179 deduction, allowing you to deduct the full purchase price in the year of acquisition.

Commercial Mortgage Interest

Interest on loans used to purchase business real estate is deductible. For mixed-use properties (part business, part personal), only the portion of interest attributable to business use qualifies.

Credit Card Interest

Interest on a business credit card used exclusively for business purchases is deductible. If you use the same card for personal and business expenses, you can only deduct the interest attributable to business charges.

What Is NOT Deductible?

Personal loan interest. If you use personal funds or a personal loan for business purposes, the interest is generally not deductible unless you can clearly document the business use.

Capitalized interest. Interest that is added to the principal balance of a loan (capitalized) rather than paid currently is not deductible until you actually pay it.

Loan principal. Repayment of the loan principal is not a deductible expense. Only the interest component qualifies.

Prepayment penalties. While some prepayment penalties may be deductible as a financing cost, the rules are complex and vary by situation. Consult a tax professional.

Merchant cash advance costs. Because MCAs are technically a purchase of future receivables rather than a loan, the factor rate cost may not qualify as deductible interest in all cases. The IRS treatment of MCA costs is evolving, and professional guidance is strongly recommended.

How to Calculate Your Deduction

For most business loans, calculating the interest deduction is straightforward:

Step 1: Review your year-end loan statement, which should itemize total interest paid during the tax year.

Step 2: If you have multiple loans, total the interest paid across all qualifying business loans.

Step 3: Report the total on your business tax return. For sole proprietors, this goes on Schedule C, Line 16a (mortgage interest) or Line 16b (other interest). For S-corps and partnerships, it goes on the applicable line of Form 1120S or 1065.

Step 4: If any loan was used for both business and personal purposes, calculate the business-use percentage and deduct only that portion.

Common Mistakes to Avoid

Mixing business and personal use. The most common audit trigger is deducting interest on a loan where funds were partially used for personal expenses. Keep business and personal borrowing strictly separate.

Failing to document loan purpose. If audited, you will need to show that borrowed funds were used for business operations. Maintain records of how loan proceeds were spent.

Deducting principal as interest. Your monthly payment includes both principal and interest. Only the interest portion is deductible. Use your loan amortization schedule to identify the split.

Overlooking construction period interest. If you borrow to construct or renovate a business property, interest incurred during construction must be capitalized and depreciated rather than deducted immediately.

Not tracking line of credit draws. Each draw on a line of credit generates its own interest calculation. Track draws, repayments, and interest charges throughout the year rather than trying to reconstruct them at tax time.

Maximize Your Deduction Strategy

Time your borrowing. If you need to make a major purchase, timing it so the interest falls within a tax year where your income is higher maximizes the value of the deduction.

Consolidate high-interest debt. Refinancing multiple high-interest obligations into a single lower-rate loan reduces your total interest cost and simplifies your deduction calculation.

Pair with Section 179. Equipment financing offers a double benefit: deduct the full equipment cost under Section 179, and deduct the loan interest as a business expense. This combination can dramatically reduce your tax burden.

Ready to explore financing options that come with tax-deductible interest? Apply through Brevo Capital and compare offers from multiple lending partners.

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Frequently Asked Questions

Is all business loan interest tax-deductible?

Interest on loans used exclusively for business purposes is generally deductible. The key requirement is that funds must be used for legitimate business expenses. Interest on personal loans used for business may also be deductible if properly documented, but mixing purposes complicates the calculation.

How do I prove to the IRS that my loan was for business use?

Maintain records showing how loan proceeds were deployed. This includes bank statements showing deposits and disbursements, invoices or receipts for purchases made with loan funds, and the loan agreement itself. Clear documentation is your best protection in an audit.

Can I deduct merchant cash advance costs?

The tax treatment of MCA costs is a gray area. Because MCAs are structured as purchases of future receivables rather than loans, the cost may not automatically qualify as deductible interest. Some businesses deduct MCA costs as a business expense rather than interest. Consult a CPA for guidance specific to your situation.

Does refinancing affect my interest deduction?

Refinancing generally does not affect your ability to deduct interest. The interest on the new loan is deductible just as it was on the old loan, provided the funds continue to be used for business purposes. Any prepayment penalties on the old loan may also be deductible.

Should I take a larger loan just for the tax deduction?

No. While the interest deduction reduces the effective cost of borrowing, you are still paying more in interest than you save in taxes. Borrow what you need for legitimate business purposes. The deduction is a benefit, not a reason to take on unnecessary debt.