Lending money to someone you love is one of the most financially dangerous things you can do — not because you’re likely to get scammed, but because good intentions and vague terms have a remarkable ability to destroy relationships and create tax headaches. The single most important decision you’ll make as a private lender isn’t whether to say yes. It’s how much interest to charge. Get this wrong and you risk an IRS problem, an unenforceable agreement, or a Thanksgiving dinner that never recovers.
Why Zero Interest Is Almost Never the Right Answer
Your instinct is to be generous, and charging interest to your brother or best friend feels wrong. But the IRS doesn’t care about your instincts. Under IRC Section 7872, the federal government imputes interest on below-market loans. If you lend money at zero percent — or at any rate below the Applicable Federal Rate (AFR) — the IRS treats the forgone interest as a taxable gift from you to the borrower, and potentially as phantom interest income to you. You can owe tax on money you never actually received.
For loans under $10,000, there’s a de minimis exception. For loans between $10,000 and $100,000, there’s a limited exception tied to the borrower’s net investment income. But for anything above $100,000 — which includes most real estate and business loans between family or friends — the imputed interest rules apply in full. Ignore them and you’re handing the IRS an easy audit target.
Beyond taxes, a zero-interest loan looks suspiciously like a gift in the eyes of courts, creditors, and bankruptcy trustees. If your borrower later faces a divorce, their spouse’s attorney will argue the “loan” was actually a gift — and therefore marital property subject to division. A written agreement with a market-rate interest charge is your best evidence that this was a real debt, not generosity dressed up in legal clothing.
The AFR: Your Floor, Not Your Ceiling
The Applicable Federal Rate is published monthly by the IRS in a Revenue Ruling and represents the minimum interest rate you should charge to avoid imputed interest problems. AFRs are broken into three tiers based on the loan term:
- Short-term (up to 3 years): Typically the lowest rate, currently hovering around 4%–4.5%.
- Mid-term (3 to 9 years): Usually slightly higher, in the range of 4%–4.5%.
- Long-term (over 9 years): Generally in the 4.5%–5% range, though this fluctuates with Treasury yields.
These rates change monthly. Always check the current month’s Revenue Ruling before finalizing your loan terms. The rate that matters is the one in effect during the month you fund the loan. Lock it in and you’re set for the life of the agreement — you don’t need to adjust if rates change later.
Think of the AFR as the floor. You can charge more. You probably should, if the loan carries real risk. What you generally cannot do — without tax consequences — is charge less.
Setting a Rate That’s Actually Fair
Fair doesn’t mean cheap. Fair means the rate reflects the risk you’re taking while still giving the borrower a genuine advantage over commercial alternatives. Here’s a practical framework:
Step 1: Start with the AFR. This is your tax-safe minimum. Charging exactly the AFR satisfies the IRS and keeps things simple.
Step 2: Consider the borrower’s commercial alternatives. If your sister could get a personal loan at 12% from her bank, lending at the AFR of 4.5% is already an enormous gift in economic terms. You don’t need to go lower to be generous.
Step 3: Factor in actual risk. Is this person employed? Do they have a history of repaying debts? Is there collateral? A loan secured by real estate is fundamentally different from a loan secured by nothing but someone’s promise. If the loan is unsecured and the borrower has shaky finances, charging a rate closer to what a bank would charge isn’t greedy — it’s rational.
Step 4: Account for the loan’s purpose. If the borrower plans to use the funds for a business or investment property, the interest they pay you may be tax-deductible for them, softening the effective cost. For purely personal use — a car, a wedding, credit card consolidation — there’s no deduction available, so you might reasonably set a lower rate. But never below the AFR.
The Gift Tax Trap Most People Miss
In 2024 and 2025, the annual gift tax exclusion is $18,000 and $19,000 respectively per recipient. If you make a below-market loan and the imputed interest exceeds this threshold, you’re required to file IRS Form 709 (Gift Tax Return). On a large loan — say $500,000 at zero percent — the annual imputed interest could easily exceed the exclusion amount, eating into your lifetime estate and gift tax exemption of $13.61 million (2024). For most people that exemption is large enough to avoid actual tax, but failing to file Form 709 is itself a compliance violation that can trigger penalties and extend the statute of limitations on the IRS’s ability to audit you — indefinitely.
Documentation That Actually Protects You
A handshake loan is barely a loan at all. At minimum, every private loan should have a written promissory note that includes:
- The principal amount and disbursement date
- The interest rate (citing the applicable AFR for the month of origination)
- A fixed repayment schedule with specific due dates
- Late payment provisions
- What happens in the event of default
- Whether the loan is secured or unsecured, and if secured, a description of the collateral
- Prepayment terms
For loans secured by real estate, you’ll also need a properly recorded deed of trust or mortgage — depending on your state — to perfect your security interest. Without recording, you’re an unsecured creditor, and you’ll be last in line if the property is sold or the borrower files for bankruptcy.
Report the interest income. Yes, you actually have to do this. Interest you receive on a private loan is taxable ordinary income, reported on Schedule B of your Form 1040. If you charge interest but don’t report it, you’ve created a discrepancy the IRS can flag through data matching, especially if the borrower deducts the same interest on their return.
When the Borrower Can Deduct Interest — and When They Can’t
Interest on a private loan is deductible by the borrower only if the funds are used for a qualifying purpose: business expenses (Schedule C), investment activity (subject to investment interest limitations), or acquisition of a qualified residence (if the loan is properly secured by the home and meets the mortgage interest deduction requirements under IRC Section 163). Interest on personal loans — no matter how well documented — is never deductible by the borrower.
This matters for rate-setting. If your friend is buying a rental property with your loan, charging a solid interest rate actually benefits them by creating a deductible expense. You’re not being harsh; you’re being tax-efficient for both sides.
The Hardest Part: What to Do When They Can’t Pay
If the borrower defaults, you may be able to claim a nonbusiness bad debt deduction — but only as a short-term capital loss, subject to the $3,000 annual net capital loss limitation. To qualify, you must prove the debt was genuine (not a gift), that you made reasonable efforts to collect, and that the debt is wholly worthless. The IRS scrutinizes these claims aggressively, especially for related-party loans. Your written promissory note, evidence of payments made, and correspondence demanding repayment are your lifeline.
The Bottom Line
Charge at least the AFR. Document everything in writing. Report the interest on your tax return. These three actions transform a risky personal favor into a legitimate financial transaction that protects your money, your relationship, and your standing with the IRS. Generosity doesn’t require you to be reckless — and the most generous thing you can do for someone you care about is structure the loan so cleanly that money never becomes the thing that comes between you.
Disclaimer: The information provided in this article is for informational purposes only and should not be considered financial or legal advice. Laws and lending criteria vary significantly between states. We always recommend consulting with a qualified real estate attorney and financial advisor before entering into a property purchase or financial arrangement with another party.
