Yes. Business loan interest payments are generally tax deductible for an S corp, an LLC or a sole proprietor when the borrowed money is spent in the business. An S corporation deducts the interest on Form 1120-S, where it lowers the ordinary business income that passes through to shareholders, and only the interest part of each payment counts. We cover the IRS tracing rules, the section 163(j) small business exemption and an after-tax example on a $150,000 loan, from IRS sources checked in November 2026.
Are business loan interest payments tax deductible for an S corp?
Yes, when the interest belongs to the corporation's trade or business. The Instructions for Form 1120-S (2025), the latest revision we found as of November 2026, say to "include only interest incurred in the trade or business activities of the corporation that isn't claimed elsewhere on the return" on line 13. That deduction reduces ordinary business income on line 22, which carries to Schedule K, line 1, and each shareholder's pro rata share is entered in box 1 of their Schedule K-1. The shareholder reports that figure on their own return, so the interest generally saves tax at the owners' rates.
The same instructions keep interest on debt used for rentals, investments or shareholder distributions off line 13 (see the table below), and they say prepaid interest "can generally only be deducted over the term of the debt."
The loan also has to be genuine debt. IRS Publication 334 (2025), the IRS tax guide for small business, lists three requirements: you're legally liable for the debt, you and the lender both intend that it be repaid, and you have a true debtor-creditor relationship.
How the use of the loan money decides the deduction
The 1120-S instructions say "debt is allocated by tracing disbursements of the debt proceeds to specific expenditures" and point to Temporary Regulations section 1.163-8T, which allocates debt "in accordance with the use of the debt proceeds." Publication 334 puts it plainly: "It doesn't matter what type of property secures the loan."
Three tracing details catch owners out:
- Parking the money. A deposit of loan proceeds in an account "is treated as an investment expenditure" until you spend it.
- Order of spending. Borrowed money in an account is treated as spent before the unborrowed money already there and before later deposits.
- The 15-day window. You may treat any payment from the account within 15 days after the deposit as made from the loan proceeds.
| Where the loan money went | Where an S corp reports the interest (2025 Form 1120-S instructions) |
|---|---|
| Equipment, inventory, payroll, rent and other operating costs | Line 13, subject to section 163(j) if it applies |
| Rental real estate | Form 8825, flowing to Schedule K, line 2 |
| Property held for investment | Schedule K, line 12c, and K-1 box 12, code H (see Form 4952) |
| Distributions to shareholders | Schedule K, line 12e, and K-1 box 12, code AC, with the amount set under Notice 89-35 |
| Producing real property or other designated property | Capitalized into the cost of the property |
For a sole proprietor, Publication 334 says "if a loan is part business and part personal, you must divide the interest," and only the business part goes on Schedule C. The regulation's repayment order moves that split over time: principal repayments are applied to the personal part first and to the trade or business part last.
Mixed-use example (assumptions labeled). A sole proprietor borrows $50,000 at an assumed 9% fixed rate over 60 months (payment $1,037.92) and spends $40,000 on equipment and $10,000 on personal bills. Month one interest is $375: $300 business and $75 personal. Because principal pays down the personal $10,000 first, business interest stays at $300 a month until the personal part is repaid in month 15, and all interest after that is business interest. First-year business interest is $3,600. Over the full term it's about $11,689 of the $12,275 total, against $9,820 if you split every payment 80/20.
LLC and sole proprietor rules: Schedule C, Form 1065 or Form 1120-S
How an LLC deducts loan interest depends on how it's taxed. The IRS LLC page (updated October 2026) says an LLC with only one member is "treated as an entity disregarded as separate from its owner," and a domestic LLC with at least two members "is classified as a partnership," unless it elects corporate treatment on Form 8832. An LLC covered by an S corporation election files Form 1120-S and follows the S corp rules above.
| Tax setup | Where business interest goes | Who applies the 163(j) limit |
|---|---|---|
| Sole proprietor, or single-member LLC owned by an individual | Schedule C, line 16a (business real property mortgage interest on a Form 1098) or line 16b (other interest) | The owner, on Form 8990 if required |
| LLC taxed as a partnership | Form 1065 | The partnership, which allocates any disallowed interest to the partners |
| LLC or corporation with an S election | Form 1120-S, line 13 | The S corporation, which carries any disallowed interest over at the corporate level |
The Schedule C instructions (2025) apply the same tracing and say that interest paid in 2025 that also applies to future years is deductible only for the part that applies to 2025. Older guides cite IRS Publication 535, but Publication 334 notes that "Pub. 535, Business Expenses, has been discontinued," so use Publication 334 and the form instructions above.
The section 163(j) interest limit and the small business exemption
Larger businesses face a cap. Business interest expense is "generally limited to the sum of business interest income, 30% of adjusted taxable income, and floor plan financing interest," per the 1120-S instructions. The Instructions for Form 8990 (Rev. December 2025) say P.L. 119-21 restored the depreciation add-back to adjusted taxable income for tax years beginning after 2024, and Publication 334 says the 2025 add-back covers depreciation, amortization and depletion. With $2,000,000 of adjusted taxable income and no business interest income or floor plan interest, the cap is $600,000.
Most owner-run companies never reach that math. "A small business taxpayer is not subject to the section 163(j) limitation and is generally not required to file Form 8990," the Form 8990 instructions say. A small business taxpayer isn't a tax shelter under section 448(d)(3) and passes this gross receipts test:
| Tax years beginning in | Average annual gross receipts, 3 prior tax years | Source |
|---|---|---|
| 2025 | $31 million or less | Form 8990 and Form 1120-S instructions |
| 2026 | $32 million or less | Rev. Proc. 2025-32, section 4.30 |
Gross receipts include those of all persons treated as a single employer, such as a controlled group of corporations or commonly controlled partnerships and proprietorships, so commonly owned businesses may have to be counted together. Certain real property and farming businesses can elect out of the limit, but the election is irrevocable and requires the alternative depreciation system for certain property.
What does a business loan cost after tax?
The after-tax cost of debt is the pre-tax interest rate times (1 minus your marginal tax rate), and the interest tax shield is the deductible interest times that rate. For an S corp, the rate that matters is the shareholder's marginal rate on the pass-through income, federal plus state.
Assumptions for this example, none of them a quote or a typical market figure:
- A $150,000 business term loan at an assumed 10% fixed rate, with 60 monthly payments of $3,187.06, funded at the start of the tax year.
- All proceeds traced to equipment and working capital, so all of the interest goes on line 13.
- The S corp passes the gross receipts test and isn't a tax shelter, so section 163(j) doesn't reduce the deduction.
- One shareholder with an assumed combined marginal rate of 30%.
| Year | Interest paid | Tax saving at 30% | After-tax interest |
|---|---|---|---|
| 1 | $13,904 | $4,171 | $9,733 |
| 2 | $11,356 | $3,407 | $7,949 |
| 3 | $8,540 | $2,562 | $5,978 |
| 4 | $5,430 | $1,629 | $3,801 |
| 5 | $1,993 | $598 | $1,395 |
| Total | $41,223 | $12,367 | $28,856 |
The 10% loan works out to 10% × (1 − 0.30) = 7% after tax; at an assumed 15% marginal rate it would be 8.5%, and at 35% it would be 6.5%. Interest is front-loaded on an amortizing loan, so most of the shield arrives in the first two years, as our loan payment examples show.
The shield only has value when there's taxable income to offset, and if the owner claims the 20% qualified business income deduction, which Publication 334 says P.L. 119-21 made permanent, a smaller business profit can shrink that deduction too. Ask your preparer to run your own rates before you use an after-tax figure to compare offers.
Principal, fees and the records to keep
Only the interest part of each payment is interest expense, since the principal repays the money you borrowed. If the loan bought equipment, its cost is recovered through depreciation or, where it qualifies, a section 179 deduction. Lender fees and points aren't always treated like stated interest, so ask your preparer how to handle any you paid.
Keep these records for each loan:
- The loan agreement, amortization schedule and the lender's year-end statement of interest paid.
- Bank records showing where the proceeds went, including the account they landed in and any payments made within 15 days.
- For an S corp, the amounts and dates of any distributions funded by the loan, for the Notice 89-35 allocation.
If you're shopping for financing, EQ Funding routes one application to lenders who compete to fund your business, including SBA loans and term loans, and lenders set any rate and terms after review. Nothing here is tax advice, so take your own figures to a CPA or enrolled agent before you file.