Issues

Bad-Debt Deductions: How To Fight a Disallowed § 166 Loss in Tax Court

You lent money you never got back, claimed a bad-debt deduction, and the IRS disallowed it. Here's how the § 166 fight really works—and what it's worth.

You lent the money in good faith. A brother starting a business, a friend in a tight spot, a small company you believed in. It was never repaid. So at tax time you claimed a bad-debt deduction for the loss—and now a Notice of Deficiency says you can't have it. The IRS isn't just disagreeing about a number; it's saying the loss you took doesn't count.

Here's the reassuring part, and the hard part, in one breath: bad-debt deductions are real and the law allows them—but they are disallowed more often than almost any other loss, and almost always for one of three specific reasons. Once you know which of the three the IRS is using, you know exactly what you have to prove.

This is the substantive merits guide to fighting a disallowed bad debt under IRC § 166. The three disallowance grounds are the spine of the whole thing:

It was never a real debt. The IRS recharacterizes your "loan" as a gift (to a relative or friend) or a capital contribution (to a company). If there was no genuine debt, there is nothing to go bad.
It's the wrong kind of debt. Most personal loans are nonbusiness bad debts—which the law treats far worse than business bad debts, and which decides how much you actually get back.
It went bad in the wrong year. A bad debt is deductible only in the year it becomes worthless. Too early and too late both lose.

A quick orientation before we start. This article is about the creditor who lent money and lost it. If you're the debtor whose forgiven debt the IRS is taxing as income, you want the mirror-image guide, Cancellation of Debt Disputes in Tax Court, instead. And one piece of reassurance that runs through everything below: the Tax Court is a prepayment forum. A timely petition lets you fight the disallowance before you pay the bill.

Ground One: Was It Even a Debt? (Bona Fide Debt vs. a Gift)

This is the single most common reason a bad-debt deduction dies—and it's where most intra-family and friend "loans" fall apart.

The rule comes from Treas. Reg. § 1.166-1(c). A bona fide debt—meaning a genuine, real debt—is one that "arises from a debtor-creditor relationship based upon a valid and enforceable obligation to pay a fixed or determinable sum of money." The same regulation says the thing that sinks most cases: a gift or a contribution to capital is not a debt for § 166 purposes.

So when you advance money to a relative or friend, the IRS's instinct is to call it a gift. When you put money into a closely held company you own, its instinct is to call it equity—a capital contribution. Either way, the conclusion is the same: there was never a "debt," so there's nothing to deduct when it isn't repaid.

Publication 550 puts it in plain English: "For a bad debt, you must show there was an intention at the time of the transaction to make a loan and not a gift. If you lend money to a relative or friend with the understanding that it may not be repaid, it is considered a gift and not a loan." It even spells out that when minor children borrow from their parents for basic needs, "there is no genuine debt."

The Badges of a Bona Fide Loan

Courts decide whether a loan was real by weighing the facts and circumstances—no single factor controls. Run your own situation against this checklist. The more boxes you can tick with contemporaneous proof (made at the time, not reconstructed later), the stronger your case:

A written promissory note stating a fixed or determinable principal.
A stated interest rate. A real lender wants interest; zero interest is a strong signal the IRS reads as "gift."
A fixed repayment schedule or maturity date.
Security or collateral, or a personal guarantee.
An actual repayment history—any payments made and accepted.
Your genuine intent and a reasonable expectation of repayment at the time the money changed hands—not hindsight after it went sour.
Demand for payment and collection efforts when the borrower defaulted. A real creditor chases the money.
Consistent treatment on the books and tax returns—recorded as a receivable, not written off as a gift.
The borrower's ability to repay when the loan was made. Advancing money to someone already insolvent looks like a gift.

Formalities Help—But Cut Both Ways

Two warnings, because readers tend to over-index on paperwork.

Transfers between family members—and from a controlling shareholder to his own company—start out presumed to be gifts or equity. You have to prove a bona fide debt to overcome that presumption.

But formalities are not conclusive in either direction. A beautifully drafted, notarized promissory note does not save an advance that everyone understood would probably never be repaid. And a genuine debt can exist without a written note if the parties' conduct—payments, demands, recorded receivables—shows real intent to repay and to collect. Papers help. They don't decide. The question is always whether a real debtor-creditor relationship existed in substance.

(The "in the business of lending" and "trade or business" questions that come up below overlap with the broader trade-or-business analysis in How To Prove Your Activity Is a Business, Not a Hobby—worth a look if the IRS is contesting whether you ran a real business at all.)

Ground Two: Business vs. Nonbusiness—Why It Decides How Much You Get Back

Say you clear the first hurdle and prove a genuine debt. The next fork decides how much your win is actually worth—and most reader loans land on the worse side of it.

Two Very Different Regimes

§ 166(a)—a BUSINESS bad debt is the good outcome. It's an ordinary deduction: it offsets ordinary income dollar-for-dollar. And it's allowed for partial worthlessness as well as total—if a business debt is recoverable only in part, you can charge off the worthless part now.

§ 166(d)—a NONBUSINESS bad debt is the bad outcome, and it's where most individual loans land. For a non-corporate taxpayer, § 166(d) turns the ordinary-deduction rule off and replaces it with two harsh consequences:

The loss is treated as a short-term capital loss—not an ordinary deduction. That triggers the capital-loss limits we'll get to in a moment.
Partial worthlessness doesn't count. A nonbusiness bad debt is deductible only when it becomes totally—wholly—worthless. Treas. Reg. § 1.166-5 is blunt: a nonbusiness debt loss is sustained "only if and when the debt has become totally worthless," and no deduction is allowed for a nonbusiness debt that is only partly recoverable.

A nonbusiness debt, in short, is any debt not created in connection with your trade or business and not one whose worthlessness is incurred in your trade or business. The character turns on whether the loss is proximately related to a trade or business of yours—and, the regulation notes, what the borrower did with the money is irrelevant.

"In the Business of Lending" Is a High Bar

Lending to a relative, a friend, or even an acquaintance's venture is nonbusiness unless you are in the trade or business of lending money—and that's a high bar. Making occasional loans, even large ones, usually isn't a lending business.

In Cooper v. Commissioner, T.C. Memo. 2015-191, the taxpayer made sporadic "hard-money" loans to friends and acquaintances and lent a half-million dollars to a real-estate development company an acquaintance ran. When it failed, he claimed a $750,000 business bad debt. The Tax Court held he was not in the business of lending—the loans were too sporadic, the recordkeeping too thin—so the loss was a § 166(d) nonbusiness debt, a short-term capital loss only. (A note for accuracy: the Cooper petitioners were represented by counsel, not self-represented. It's a clean merits authority on the lending-business line, not a pro se story.)

The Shareholder-Guarantee Trap and the "Dominant Motivation" Test

There's a classic version of this fight that catches small-business owners. You own stock in your company, you also draw a salary from it, and you personally guarantee the company's bank loan. The company fails, you pay off the loan, and you want a business bad debt—on the theory that you were protecting your job.

The Supreme Court closed that door in United States v. Generes, 405 U.S. 93 (1972). The test for whether your loss is "proximately related" to a trade or business—your employment—versus your investment as a shareholder is dominant motivation, not merely a significant one. In the Court's words, "the proper measure is that of dominant motivation, and that only significant motivation is not sufficient."

Here's why that almost always hurts the guarantor: protecting a stock investment—your capital—is treated as the dominant motive, not protecting a salary. So the shareholder who guarantees company debt usually loses the business characterization, and the loss drops to a nonbusiness short-term capital loss. Knowing this going in saves you from building a case on the weaker theory.

The $3,000 Reality Check: What a Nonbusiness Win Is Actually Worth

This is the expectation to set before you spend months fighting—because a winning nonbusiness bad-debt claim may give you almost no tax benefit this year. And assume yours is nonbusiness: it almost always is, unless you lend money for a living or the debt arose in your own trade or business. So this is the number that matters to most readers here.

Because a nonbusiness bad debt is a short-term capital loss, it doesn't offset your salary or other ordinary income directly. It first offsets your capital gains. Only the excess touches ordinary income—and only up to $3,000 a year (IRC § 1211(b); $1,500 if you're married filing separately). Everything above that carries forward to future years, keeping its short-term character (IRC § 1212(b))—$3,000 at a time, indefinitely, until it's used up.

Put real numbers on it. You lent $50,000, it's a bona fide nonbusiness debt, it's wholly worthless, and you have no capital gains that year. Your deduction against ordinary income this year is $3,000. The remaining $47,000 carries forward and chips away at $3,000 a year (faster only if you have capital gains to absorb it). So "winning" a $50,000 bad-debt fight might save you only a few hundred dollars in tax this year.

Now the contrast that explains why the IRS fights so hard over Ground Two. The same $50,000 as a business bad debt is an ordinary deduction—the full $50,000 offsets ordinary income now, and partial worthlessness would have been allowed too. Business versus nonbusiness can be the difference between a $50,000 deduction this year and a $3,000 one. That's the whole ballgame.

The $3,000 cap and the carryforward mechanics live in detail in Cost Basis Disputes in Tax Court, which owns the capital-gain-and-loss machinery—head there for how the limit and the carryover actually compute. The point to carry here is the consequence: don't over-invest in a nonbusiness claim that yields $3,000 a year, and fight hard for business characterization when the facts genuinely support it.

Ground Three: Worthless—and in Which Year?

The third disallowance ground is timing, and it's the subtlest. A § 166 deduction is allowed only in the tax year the debt becomes worthless—and for a nonbusiness debt, wholly worthless. Claim it too early, while there's still some hope of recovery, and it's disallowed. Claim it too late—in a year after it actually went bad, or after that earlier year is closed—and it's disallowed too. You have to hit the year.

There's no mechanical test. Worthlessness is shown by identifiable events that give reasonable grounds for abandoning any hope of recovery. Your private belief that you'll never see the money isn't enough; you need something objective. The events courts accept include:

The debtor's bankruptcy or insolvency.
The debtor's business ceasing or being dissolved.
The debtor's death without an estate to pay from.
The debtor absconding or disappearing.
Other proof that collection—even by lawsuit—would be futile.

Pub. 550 is encouraging on the last point: "It is not necessary to go to court if you can show that a judgment from the court would be uncollectible. You must only show that you have taken reasonable steps to collect the debt." And it confirms that "bankruptcy of your debtor is generally good evidence of the worthlessness of at least a part of an unsecured and unpreferred debt."

The Counter-Intuitive Trap: Trying to Collect Can Defeat Your Claim

Here's the part that surprises people. Taking steps to recover your money can be used against a same-year worthlessness claim. If you filed a proof of claim in the debtor's bankruptcy, you were—by your own action—still hoping to recover. That cuts against the debt being wholly worthless that year.

That's exactly what sank the taxpayers in Bunch v. Commissioner, T.C. Memo. 2014-177—a genuine pro se case, the kind of scenario that lands real people here. The Bunches and their family had loaned millions to a mortgage company that turned out to be running a fraud. They claimed a multi-million-dollar bad-debt loss for 2006. The Tax Court held it was a nonbusiness debt (they were ordinary investors, not in the company's trade or business), so it was deductible only if wholly worthless in 2006—and it wasn't. They had filed a proof of claim in the company's bankruptcy (which the court said "tends to establish the reverse" of worthlessness), the bankruptcy estate's value was still unknown at year-end, and the bankruptcy court later authorized partial distributions to creditors. As of December 31, 2006, they couldn't show reasonable grounds for abandoning all hope of recovery. Deduction denied.

Cooper lost on this ground too. There, the taxpayer listed the loan as an asset on his own net-worth statements into 2009 and didn't treat it as worthless until a 2010 amended return retroactively claiming 2008. The court found the loan's "last vestige of value" wasn't gone in the years claimed. The lesson from both cases: you have to nail both the character and the worthlessness year. Getting one right doesn't save you if you miss the other.

The 7-Year Escape Hatch If You Claimed the Wrong Year

There's a safety valve worth knowing. If you discover a debt was actually worthless in an earlier year—maybe the IRS just told you so by disallowing the year you picked—you usually aren't out of luck. Pub. 550 confirms a special 7-year window for bad debts: you can file Form 1040-X to claim it "within 7 years from the date your original return for that year had to be filed, or 2 years from the date you paid the tax, whichever is later." That's far longer than the normal 3-year refund window, and it exists precisely because pinning the worthlessness year is so hard.

Build Your Proof File and Report It Right

Whether you're heading off a proposed adjustment or already in Tax Court, the burden is on you to prove the deduction (IRC § 7491; Tax Court Rule 142(a); Welch v. Helvering, 290 U.S. 111 (1933)). Deductions are a matter of legislative grace, and a bad-debt deduction is no exception. Here's the file that wins.

The Four Things Your File Must Show

The loan terms and your intent. The note or loan agreement, plus any contemporaneous emails or texts showing the deal and a real expectation of repayment. This is your Ground One evidence.
Proof the money actually moved—and that you have basis. Cancelled checks, wire confirmations, bank statements. You can't deduct a "loan" you can't prove you funded. And you need basis: Pub. 550 says "to deduct a bad debt, you must have a basis in it—that is, you must have already included the amount in your income or loaned out your cash." No basis means no deduction—which is why you can't deduct unpaid wages, salary, rent, or interest you never reported as income in the first place.
Collection efforts. Demand letters, texts and emails chasing payment, a small-claims filing—or a contemporaneous record of why suing would be futile (the debtor is judgment-proof, vanished, or insolvent). This serves double duty: it supports both the bona fide debt and the worthlessness.
The dated worthlessness event. The bankruptcy filing or discharge, the business dissolution, the debtor's death or insolvency—the thing that pins the year.

The Bad-Debt Statement: A Template That Doubles as Your Exhibit

Treas. Reg. § 1.166-1(b) requires you to attach a statement of the facts supporting the deduction to your return. Pub. 550 spells out what it must contain. Build it as a fill-in-the-blanks document (the loan-terms line is an extra worth adding)—it's both your return attachment and a ready-made Tax Court exhibit:

A description of the debt, including the amount and the date it became due: _______

The debtor's name, and any business or family relationship between you and the debtor: _______

The terms of the loan (date, principal, interest rate, maturity, security): _______

The efforts you made to collect the debt: _______

Why you decided the debt was worthless, and when—for example, the debtor went bankrupt, or you cannot collect a court judgment: _______

How a Nonbusiness Bad Debt Goes on the Return

The mechanics, straight from Pub. 550 and the Form 8949 instructions:

Report it as a short-term capital loss on Form 8949, Part I, with Box C checked (because there's no Form 1099-B for it).
In column (a), enter the debtor's name and "bad debt statement attached."
In column (d) (proceeds), enter zero. In column (e), enter your basis in the bad debt. Use a separate line for each bad debt.
It then carries to Schedule D as a short-term loss—where the $3,000 limit and carryforward kick in.

One precision note so you don't trip on the form: a nonbusiness bad debt does not use a column-(f) adjustment code. The Form 8949 instructions don't assign one. The entry is simply the debtor's name plus "bad debt statement attached" in column (a), zero proceeds in (d), and your basis in (e). Don't invent a code that isn't there.

If the IRS Already Disallowed It: The Tax Court Forum

When the IRS disallows your bad debt, it usually lands in a Notice of Deficiency—the 90-day letter. That document starts your clock.

Read the notice (or the CP2000 or Form 4549) to find which of the three grounds the IRS used. "Not a bona fide debt," "nonbusiness, not business," or "wrong year"—the fix is different for each, and the IRS sometimes stacks more than one. Identifying the ground tells you which part of this guide is your fight. Sanity-check the dollar figure, too: the adjustment should equal the bad-debt deduction you claimed (or, if the IRS concedes nonbusiness character, the amount over the $3,000 capital-loss limit). If it doesn't match, that discrepancy is itself worth raising.
You have 90 days from the date on the Notice of Deficiency to petition the Tax Court (150 days if it was addressed outside the US). The deadline cannot be extended, and you don't have to pay first.
The burden is yours—to prove the bona fide debt, its character, and the worthlessness year (§ 7491; Rule 142(a); Welch).
Know your downside. If you lose, the disallowed loss is added back as a deficiency, with interest running from the original due date, and the IRS may add a 20% accuracy-related penalty under § 6662 if the underpayment is large enough. The flip side: a genuine, well-documented loan position—even one that loses on the year or the character—is a strong reasonable-cause defense to that penalty. See How To Fight the IRS Accuracy Penalty.
Most disputes settle. Most (76%) of Tax Court cases close by formal settlement, and once you put a documented bad-debt file in front of IRS Counsel, many of these resolve without a trial.
If your deficiency is $50,000 or less per year, you can elect small-case ("S") procedures—simpler and less formal.

The procedural how-to for filing lives in How To File Your Tax Court Petition, so this guide doesn't repeat it. The filing fee is $60, with a waiver available.

What To Do Now

If a disallowed bad debt is in front of you:

Calendar the 90 days deadline on any Notice of Deficiency. It cannot be extended.
Identify which of the three grounds the IRS used—bona fide debt, business vs. nonbusiness, or wrong year—from the notice, CP2000, or Form 4549.
Build your proof file: the note and loan terms, proof you funded the loan, your collection efforts, and the dated worthlessness event.
Assemble the bad-debt statement using the template above—it's both a return attachment and your exhibit.
Be honest with yourself about character and value. If it's nonbusiness, a win is a short-term capital loss worth $3,000 a year against ordinary income—so weigh the fight accordingly. If the facts support a business bad debt, that's where the real money is.
If you may have claimed the wrong year, remember the 7-year Form 1040-X window for a debt worthless in an earlier year.
Decide whether to petition. A timely petition preserves your prepayment forum and your right to contest the disallowance before paying.

Around 89% of Tax Court petitioners represent themselves, though the win rate trails represented petitioners (about 12% pro se versus about 23% represented in the most recent NTA data). A documented bad-debt case—where the fight is really about assembling the record—can suit self-representation, but a large loss or a contested business-versus-nonbusiness call is where help pays off. See When To Get Professional Help With Your Tax Dispute. And if your income is at or below 250% of the poverty line and your dispute is at or below $50,000, a Low Income Taxpayer Clinic may take your Tax Court case for free.

Resources

Statutes and regulations:

IRS forms and publications:

Cases cited:

United States v. Generes, 405 U.S. 93 (1972)
Welch v. Helvering, 290 U.S. 111 (1933)
Cooper v. Commissioner, T.C. Memo. 2015-191 (U.S. Tax Court, DAWSON)
Bunch v. Commissioner, T.C. Memo. 2014-177 (U.S. Tax Court, DAWSON)

Companion articles on TaxCourtHelp:

This article is for informational purposes only and does not constitute legal or tax advice. For advice specific to your situation, consult a qualified tax professional or attorney.