Debt service is not an operating expense. Operating expenses are the ordinary costs of running the business—rent, payroll, utilities, insurance, supplies—while debt service is the principal and interest you pay on borrowed money. Accounting standards, tax rules, and lender analyses all keep the two categories apart, and treating them as the same thing can distort your profit picture, cost you deductions, or draw an IRS penalty.
What Operating Expenses Cover
Operating expenses are the recurring costs tied to producing revenue. Federal tax law lets a business deduct “all the ordinary and necessary expenses paid or incurred during the taxable year in carrying on any trade or business,” which includes reasonable employee compensation, business travel, and rent for property the business uses but does not own. In practice, that means rent, wages and benefits, utilities, marketing, insurance, and the supplies consumed in delivering your product or service.
Subtract these from revenue and you get operating income, a measure of how well the core business performs before any financing decisions enter the picture.
What Debt Service Is
Debt service is the total cash a business must pay on its loans during a period. It has two parts:
- Principal, the portion that pays down the original amount borrowed and reduces the outstanding balance.
- Interest, the lender’s charge for the use of its capital, calculated as a percentage of the remaining balance.
These payments exist because the business chose to fund purchases—equipment, real estate, working capital—by borrowing rather than paying cash. They reflect how the business is financed, not how efficiently it operates. Two companies with identical revenue and identical operating costs can post very different bottom lines depending on how much debt each one carries. That is exactly why the accounting rules put debt service in a different bucket.
Where Interest and Principal Appear on Financial Statements
Income Statement
Operating expenses come out of revenue to produce operating income, also called earnings before interest and taxes (EBIT). Interest expense sits below the EBIT line because it is a cost of financing, not operations. Subtract interest and taxes from EBIT and you get net income.
Principal payments do not appear on the income statement at all. Repaying borrowed money is not an expense—it reduces a liability. The original loan proceeds were not income when you received them, so returning them is not an expense when you pay them back.
Balance Sheet
Each principal payment reduces the loan balance under liabilities, and cash on the asset side falls by the same amount. Interest flows through the income statement as an expense and reduces retained earnings.
Statement of Cash Flows
Under generally accepted accounting principles, the cash flow statement splits debt service in two. Interest payments show up as operating cash outflows. Principal payments show up as financing cash outflows. That split lets anyone reading the statements see how much cash it takes to run the business versus how much it takes to service the capital structure.
Tax Treatment: Interest Is Deductible, Principal Is Not
The two components of debt service are taxed very differently. Federal law allows a deduction for “all interest paid or accrued within the taxable year on indebtedness” when the debt is connected to a trade or business.1Office of the Law Revision Counsel. 26 USC 163 – Interest The interest portion of your loan payments reduces taxable income.
Principal gets no deduction. The loan proceeds were not taxed as income when you received them, so returning them is not an expense. This is where owners often get surprised: you can write a large monthly check to the lender and only get a tax benefit for the interest slice of it.
Operating expenses, by contrast, are generally deductible in full in the year incurred. Getting the split right on your return matters. Overstating deductions by treating principal payments as expenses can trigger an accuracy-related penalty of 20 percent of the resulting underpayment, on top of the tax and interest already owed.2Internal Revenue Service. 20.1.5 Return Related Penalties
The Section 163(j) Limit on Interest Deductions
Even though interest is generally deductible, larger businesses face a cap. Section 163(j) limits the business interest a company can deduct in a year to the sum of its business interest income plus 30 percent of its adjusted taxable income (ATI). Interest that exceeds the cap is not lost; it carries forward and can be deducted in a later year when there is room under the limit.3Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense4eCFR. 26 CFR 1.163(j)-5 – General Rules Governing Disallowed Business Interest Expense Carryforwards for C Corporations
For tax years beginning after December 31, 2024, depreciation, amortization, and depletion are added back when calculating ATI. Capital-intensive businesses with large depreciation deductions will therefore have a higher ATI for 2026 and later, which raises the amount of interest they can deduct.3Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense
Small Business Exemption
The cap does not apply to every business. If your average annual gross receipts over the prior three tax years fall at or below the inflation-adjusted threshold—$32 million for 2026—you can deduct the full business interest expense with no 163(j) limit.3Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense
Partnerships and S Corporations
Partnerships apply the 163(j) limit at the partnership level. If interest exceeds the cap, each partner is allocated a share of the disallowed amount (excess business interest expense) and can only use it later when the same partnership generates enough excess taxable income or excess business interest income. S corporations apply the limit at the entity level as well, but disallowed interest stays with the S corporation and carries forward there rather than passing through to shareholders.3Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense
When Interest Has to Be Capitalized Instead
Some interest cannot be deducted in the current year at all, even if it fits within the 163(j) cap. Under Section 263A, interest must be capitalized into the cost of an asset when the business is producing real property or tangible personal property that has a long useful life, a production period exceeding two years, or a production period exceeding one year with a cost above $1,000,000.5Office of the Law Revision Counsel. 26 USC 263A – Capitalization and Inclusion in Inventory Costs of Certain Expenses The capitalized interest becomes part of the asset’s depreciable basis and is recovered over the asset’s useful life instead of being deducted the year it was paid.
This mostly affects businesses that construct their own buildings, manufacture large equipment, or develop real estate. Interest on a line of credit used for ordinary operations generally does not fall under this rule.
Why Lenders Watch This Distinction Too
Lenders rely on the operating income versus debt service split to judge whether you can repay. The debt service coverage ratio (DSCR) divides earnings before interest, taxes, depreciation, and amortization (EBITDA) by total annual debt service, meaning interest plus principal. A DSCR of 1.0 means earnings exactly cover debt payments with nothing left over. Most commercial lenders want at least 1.25, giving a 25 percent cushion.
If your statements bury debt service inside operating expenses, operating income drops and the DSCR calculation stops meaning anything. Keeping the categories separate is not just an accounting formality. It affects whether the next loan gets approved, and at what rate.
What Goes Wrong When You Misclassify
On the tax side, treating principal payments as deductible expenses overstates deductions and understates taxable income. The IRS treats significantly overstated deductions as negligence, and the accuracy-related penalty runs 20 percent of the underpayment, plus the original tax and interest from the filing deadline.2Internal Revenue Service. 20.1.5 Return Related Penalties
On the reporting side, folding debt service into operating expenses inflates operating costs and deflates operating income, making the core business look weaker than it is. Investors, lenders, and potential buyers all read operating income to gauge the health of the company. Distorting that number can sink a loan application, drag down a valuation, or raise problems during due diligence. Keep interest on its own line below EBIT, keep principal off the income statement entirely, and the tax return and the financial statements will both hold up.