Interest a shareholder charges on a loan to a closely held corporation is deductible by the corporation as business interest and taxable to the shareholder as ordinary income, provided the IRS accepts the arrangement as genuine debt. That single condition drives the entire tax treatment of shareholder loan interest, because if the loan gets recharacterized as a capital contribution, the corporation loses the deduction and the payments become dividends or distributions to the shareholder. Getting the structure right up front is cheaper than defending it on audit.
What Makes It a Real Loan in the IRS’s Eyes
The IRS looks past labels. A promissory note titled “Loan Agreement” does not settle the question if the surrounding facts point to equity. Section 385 of the Internal Revenue Code lists factors including a written promise to pay a fixed sum with interest, whether the obligation is subordinated to other corporate debts, the corporation’s debt-to-equity ratio, and the overlap between stock ownership and loan holdings.1Office of the Law Revision Counsel. 26 USC 385 – Treatment of Certain Interests in Corporations as Stock or Indebtedness Courts add more, and no single factor decides the case.
Four things do most of the work in practice.
A Written Note With Real Terms
A promissory note should state the principal, a fixed maturity date, a repayment schedule for principal and interest, and a stated interest rate. The board of directors should approve the loan through a formal resolution recorded in the minutes or a written consent, the same way it would approve any third-party financing. Without an enforceable written agreement and corporate authorization, the IRS has a straightforward argument that the transfer was a capital contribution.
An Interest Rate That Matches the Market
The stated rate has to reflect what an unrelated lender would charge. The benchmark is the Applicable Federal Rate published monthly by the IRS. For February 2026, the short-term AFR (loans of three years or less) is 3.56%, the mid-term AFR (over three years up to nine years) is 3.86%, and the long-term AFR (over nine years) is 4.70%, all compounded annually.2IRS. Revenue Ruling 2026-3 Charging less than the AFR triggers the imputed interest rules under Section 7872, discussed further below.3Office of the Law Revision Counsel. 26 USC 7872 – Treatment of Loans With Below-Market Interest Rates
Actual Repayment
The shareholder-lender must hold the same rights as an outside creditor, including the ability to demand repayment and enforce the note. If the corporation skips payments for years and no one enforces the note, the IRS will argue there was never any real debtor-creditor relationship. Repeatedly extending the maturity date is nearly as damaging. Treat the note the way a bank would treat one, because that is exactly the comparison the IRS will draw.
Adequate Capitalization
A corporation funded almost entirely with shareholder loans and very little equity is thinly capitalized, one of the strongest indicators of recharacterization. No single debt-to-equity ratio automatically triggers reclassification, but ratios above 3-to-1 tend to attract scrutiny. Collateral helps too. When a shareholder loan is unsecured while the company’s bank debt is fully secured, the IRS can reasonably argue the shareholder is putting capital at risk rather than lending money.
How the Corporation Deducts the Interest
When the loan qualifies as genuine debt, the corporation deducts the interest as a business expense under Section 163.4Office of the Law Revision Counsel. 26 USC 163 – Interest The mechanics depend on the entity type.
C-Corporations
A C-corporation deducts the interest expense directly against gross income on Form 1120. With the flat 21% federal corporate rate, every dollar of deductible interest reduces federal tax by roughly 21 cents. That is a major reason owners of closely held C-corporations often prefer debt financing over equity contributions.
S-Corporations
An S-corporation typically pays no entity-level federal tax. The interest deduction flows through to shareholders on Schedule K-1, reducing each shareholder’s individual taxable income on a pro-rata basis.5Internal Revenue Service. Instructions for Schedule K-1 Form 1120-S Shareholder loans to an S-corporation also create debt basis, separate from stock basis. If corporate losses exceed a shareholder’s stock basis, the shareholder can still deduct losses up to the amount of debt basis from loans they personally made. A loan guarantee is not enough; the shareholder must have actually lent the money directly.6Internal Revenue Service. S Corporation Stock and Debt Basis
The Section 267 Timing Trap
This one catches a lot of closely held businesses. When a shareholder owns more than 50% of the corporation’s stock (counting direct and constructive ownership), the two are related persons under Section 267.7Office of the Law Revision Counsel. 26 USC 267 – Losses, Expenses, and Interest With Respect to Transactions Between Related Taxpayers If the corporation uses the accrual method and the shareholder uses the cash method, the corporation cannot deduct accrued interest until the shareholder actually receives the payment and reports it as income.
An accrual-basis corporation that books interest expense at year-end but writes the check in January cannot take the deduction in the earlier year. The fix is simple: pay the interest before year-end so the deduction and the income land in the same tax year.
How the Shareholder Reports the Income
Interest the shareholder collects on a legitimate loan is ordinary income taxed at the shareholder’s marginal rate.8Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined There is no preferential rate the way there is for qualified dividends. The shareholder reports the income on Schedule B of Form 1040, and the corporation issues Form 1099-INT once total interest paid to the shareholder reaches $10 or more for the year.9Internal Revenue Service. Instructions for Forms 1099-INT and 1099-OID
For shareholders who do not materially participate in the corporation’s operations, interest income could be passive under Section 469.10Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited The self-charged interest regulations prevent a mismatch where a shareholder would end up with passive interest income on one side and a non-passive interest deduction flowing through from the entity on the other. They recharacterize the shareholder’s interest income as non-passive to the extent the entity’s corresponding interest deduction is non-passive. For owner-operators who materially participate, this keeps income and deduction in the same bucket.
Below-Market Loans and Imputed Interest
Section 7872 targets below-market loans between a corporation and its shareholders.3Office of the Law Revision Counsel. 26 USC 7872 – Treatment of Loans With Below-Market Interest Rates When a shareholder charges less than the AFR, the IRS treats the shortfall as if it had actually been paid, creating phantom cash flows with real tax consequences.
The gap between AFR interest and actual interest is the forgone interest. The IRS treats this as two transactions: the corporation transferred the amount to the shareholder (typically as a deemed dividend), and the shareholder then paid it back to the corporation as interest. Both sides face tax consequences on money that never moved.
Take a shareholder who lends $200,000 to the corporation at 0% when the applicable AFR is 3.86%. The forgone interest of roughly $7,720 for the year is a deemed dividend from the corporation to the shareholder and a deemed interest payment from the shareholder to the corporation. The shareholder has taxable dividend income and imputed interest income. The corporation gets a deduction for the imputed interest but cannot deduct the deemed dividend. The net result is worse than simply charging the AFR to begin with.
There is a narrow safe harbor. Corporation-shareholder loans are exempt from the imputed interest rules if the total outstanding balance between the parties stays at or below $10,000 on every day of the year. The threshold is aggregate: if multiple advances together cross $10,000 on any single day, the rules apply to the full balance, not just the excess. A separate de minimis rule in Section 7872(d) tied to the borrower’s net investment income exists, but it applies only to gift loans between individuals, not to corporation-shareholder loans. Relying on the wrong exception is a costly mistake.
When imputed interest creates original issue discount and the annual OID reaches $10, the corporation reports it on Form 1099-OID instead of Form 1099-INT. For loans of one year or less, any OID goes on Form 1099-INT.9Internal Revenue Service. Instructions for Forms 1099-INT and 1099-OID
The Section 163(j) Business Interest Cap
Even legitimate shareholder loan interest can hit a ceiling. Section 163(j) limits a taxpayer’s deductible business interest expense for the year to business interest income plus 30% of adjusted taxable income.11Internal Revenue Service. Questions and Answers About the Limitation on the Deduction for Business Interest Expense Disallowed interest carries forward indefinitely.
Small businesses are exempt. A corporation (or group of related entities) whose average annual gross receipts over the prior three years stay at or below the inflation-adjusted threshold ($31 million for 2025, with a slightly higher figure expected for 2026) is not subject to the 163(j) limitation. For most closely held companies the cap is irrelevant, but owners of higher-revenue businesses need to model the limitation before structuring large shareholder loans.
What Happens If the Loan Gets Reclassified
When the IRS successfully recharacterizes a shareholder loan as a capital contribution, the consequences cascade through both returns.
- The corporation loses every dollar of interest deduction it previously claimed, owes additional tax on the recaptured income, and pays interest on the underpayment from the original due date.
- For a C-corporation, the reclassified payments become dividends, potentially eligible for the qualified dividend rate but still taxable to the shareholder and non-deductible to the corporation. For an S-corporation, the payments are distributions that reduce stock basis and become capital gain once basis runs out.
- The corporation files an amended Form 1120 or 1120-S to remove the disallowed deductions, and the shareholder may need to amend Form 1040 to reclassify the income.
- The corporation reports the reclassified payments on Form 1099-DIV rather than Form 1099-INT.12Internal Revenue Service. Instructions for Form 1099-DIV
Losing the corporate deduction while the shareholder still owes tax on the payments is what makes reclassification so expensive.
Penalties and How Long the IRS Has to Act
The IRS generally has three years from the date a return is filed (or its due date, whichever is later) to assess additional tax. If a reclassified shareholder loan causes the taxpayer to report 25% or less of actual income, the window extends to six years. Fraudulent returns face no time limit.13Internal Revenue Service. Time IRS Can Assess Tax
Accuracy-related penalties under Section 6662 apply at 20% of the underpayment when it results from negligence, disregard of rules, or a substantial understatement of income tax.14Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments A gross valuation misstatement raises the penalty to 40%. These penalties stack on top of the additional tax and interest, so a documentation problem can become very expensive very quickly. Formal loan documentation, market-rate interest, and a real repayment history are the most straightforward defense, because they demonstrate reasonable cause and good-faith compliance and can eliminate the penalty even if the IRS ultimately wins the debt-versus-equity question.