What’s the Penalty for a Wash Sale? (w/Examples) + FAQs

This article reflects federal IRS rules and general state-conformity rules as of June 2026 and covers tax year 2025 (the 2026 filing season). Tax law changes — confirm current figures before you file.

Quick Answer

There is no IRS fine for a wash sale. For tax year 2025, the “penalty” is that the IRS disallows your capital loss in the year you sell. You do not lose the loss forever in a taxable account — it shifts onto the cost basis of the replacement shares and counts later when you finally sell those shares.

A wash sale is not a violation you get punished for. It is a timing rule. You sell a stock at a loss, you buy the same stock back within 30 days, and the IRS under Section 1091 says you cannot claim that loss right now. The immediate consequence is a bigger tax bill this year, because the loss you were counting on to offset gains gets erased from your current return.

The stakes grow when the rule bites in the wrong place. In a normal taxable account the loss is only delayed. But if you repurchase inside an IRA, Revenue Ruling 2008-5 makes the loss vanish for good. And if you misreport a wash sale, a separate 20% accuracy-related penalty can land on top — that is the real fine people fear.

📉 The true cost of a wash sale and why it is a deferral, not a fine.
🔁 How the disallowed loss moves to your new shares’ cost basis (with the math).
🏦 Why an IRA repurchase destroys the loss permanently — the worst-case trap.
🧾 How to report a wash sale on Form 8949 and Schedule D so the IRS does not add a 20% penalty.
🪙 Whether the rule applies to crypto in 2026 and the pending law that could change it.

What a Wash Sale Actually Is

A wash sale happens when you sell a stock or security at a loss and buy a “substantially identical” one within a set window around that sale. The IRS defines this window as 61 days: the day of the sale, the 30 days before it, and the 30 days after it. People call it the “30-day rule,” but the full trap covers 61 days because it looks both backward and forward.

The rule lives in Internal Revenue Code Section 1091. Congress wrote it to stop a simple trick: selling a stock just to book a tax loss, then buying it right back so your real investment never changed. Without the rule, you could harvest a paper loss every December and keep the exact same portfolio. The IRS calls that an artificial loss, and Section 1091 disallows it.

The consequence of triggering the rule is that your loss is “disallowed” for the current year. Disallowed does not mean deleted in a normal brokerage account. It means the loss is parked. You cannot use it now, but the rule moves it onto the replacement shares so you can use it later. The misconception here is huge: many investors think a wash sale means the IRS keeps their money or fines them. It does not. What you should do is simply track the adjusted basis of your new shares, because that is where your loss is waiting.

The 61-Day Window

The window is 61 days long, not 30. It starts 30 days before your sale date and ends 30 days after it. So a purchase you made before you sold at a loss can trigger the rule just as easily as one you make after.

The consequence of forgetting the “before” half is the most common surprise on a 1099-B. You sell shares at a loss in January, but you happened to buy more of that same stock in late December — within 30 days before the sale — and the loss is disallowed. What you should do is count 30 days back and 30 days forward from every loss sale, and check both halves before you trade.

What “Substantially Identical” Means

The hardest part of the rule is that the IRS never gave a clear definition of “substantially identical.” You have to use judgment. Stock in one company is almost never identical to stock in a different company, so selling Coca-Cola and buying PepsiCo is fine. But selling and rebuying the same company’s shares clearly counts.

The gray zone is index funds and ETFs. Two S&P 500 funds from different companies track the same index but are legally separate securities, so most advisors treat them as not substantially identical. JPMorgan suggests a test: would a knowledgeable investor see a real economic difference between the two positions? If not, they are likely substantially identical, and the wash sale rule could apply even to two different tickers. When in doubt, what you should do is pick a replacement that tracks a different index.

Which Situation Applies to You?

The wash sale rule plays out very differently depending on where you trade and what you own. Find your situation below, then read the section that fits you.

You trade in one regular brokerage account. Your loss is only delayed. It moves to your new shares’ basis. Read the basis-adjustment section.
You bought the loss stock back inside an IRA or Roth IRA. This is the worst case. The loss is gone forever. Read the IRA section.
You and your spouse trade separately. The IRS treats a married couple as one taxpayer for this rule, so your spouse’s purchase can trigger your wash sale. Read the named examples.
You get RSUs, ESPP shares, or use dividend reinvestment. Automatic purchases can trigger accidental wash sales. Read the mistakes section.
You trade crypto. For 2026, the rule generally does not apply to crypto, but a bill could change that. Read the crypto section.

The Real “Penalty”: Loss Deferral and Basis Adjustment

In a taxable account, the wash sale rule does not take your loss away. It defers it. The disallowed loss is added to the cost basis of the replacement shares you bought. So when you eventually sell those replacement shares, your basis is higher, your gain is smaller (or your loss is bigger), and you recover the benefit then.

The holding period also carries over. The time you held the original shares gets added to the holding period of the replacement shares. That can help you reach long-term capital gains treatment sooner. The consequence of not tracking this is that you overpay later — you forget your basis was bumped up and report too large a gain.

Here is the fully worked math. Say you buy 100 shares of a stock at $50, for a $5,000 cost. You sell all 100 at $40, for $4,000, locking in a $1,000 loss. Within 30 days you rebuy 100 shares at $42, for $4,200. The wash sale rule disallows the $1,000 loss now. Instead, that $1,000 is added to your new basis: $4,200 + $1,000 = $5,200 adjusted basis. Later you sell those shares at $60, for $6,000. Your taxable gain is $6,000 − $5,200 = $800, not the $1,800 it would have been without the adjustment. The $1,000 loss was never lost — it shrank your future gain by exactly $1,000.

The Worst Case: A Wash Sale Inside an IRA

The one place a wash sale truly costs you the whole loss is an IRA. If you sell a stock at a loss in your taxable account and rebuy a substantially identical stock in your traditional IRA or Roth IRA within the 61-day window, the loss is disallowed — and the IRS will not let you add it to the IRA’s basis.

This comes straight from Revenue Ruling 2008-5. The IRS ruled that the loss is disallowed under Section 1091 and the basis of the stock in the IRA is not increased. Because IRAs do not track cost basis the way taxable accounts do, the loss is permanently gone. There is no future sale that gives it back to you.

The consequence is brutal: a $1,000 loss you expected to use simply disappears, with no offset ever. The common misconception is that “it’s all my money, so it doesn’t matter which account buys the shares.” It matters enormously. What you should do is never repurchase a loss security in any IRA within 30 days of selling it at a loss in a taxable account — and remember the rule counts purchases your IRA made in the 30 days before the sale too.

When the IRS Adds a Real Penalty on Top

The wash sale itself carries no fine. But a real, separate penalty can stack on if you handle it wrong. If you ignore a wash sale your broker reported, claim the disallowed loss anyway, and underpay your tax, the IRS can assess an accuracy-related penalty under IRC Section 6662.

This penalty is 20% of the underpayment caused by negligence or a substantial understatement of income tax. So if claiming a disallowed $5,000 loss cut your tax by $1,100, and the IRS catches it, you owe that $1,100 back plus a $220 penalty (20%), plus interest from the original due date. The consequence grows the longer it goes unnoticed, because interest keeps running. What you should do is report every wash sale your 1099-B flags, even when it feels unfair, and keep the records that show your math.

How to Report a Wash Sale: Form 8949 and Schedule D

You report wash sales on IRS Form 8949, then carry the totals to Schedule D. Both attach to your Form 1040, due April 15, 2026, for the 2025 tax year. Your broker already flags the disallowed amount on your 1099-B in the box labeled “wash sale loss disallowed.”

On Form 8949, you list the sale in columns (a) through (e): description, dates, proceeds, and cost basis. Then you enter code W in column (f) to mark a wash sale. In column (g) you enter the disallowed loss as a positive adjustment, which reduces the loss you actually claim. Column (h) shows your allowed gain or loss after the adjustment. The consequence of skipping code W is a mismatch with the 1099-B the IRS already received, which often triggers a notice.

If your full loss is disallowed, the adjustment in column (g) equals the loss, and your column (h) result is zero. If only part is disallowed — say you rebought only some of the shares — only that portion is adjusted. What you should do is match each line to your 1099-B figures, enter code W everywhere your broker flagged it, and keep a worksheet showing how you split partial wash sales. Learning how to fill out Form 8949 line by line is the single best way to avoid a 20% penalty here.

Does Your State Follow the Wash Sale Rule?

The wash sale rule is a federal rule. Most states that tax capital gains start from your federal taxable income, so they automatically follow the federal wash sale treatment. In those states, a loss disallowed federally is disallowed on your state return too.

The clean exceptions are the no-income-tax states. States like Florida, Texas, Washington, Nevada, South Dakota, Wyoming, Alaska, and Tennessee do not tax personal capital gains at all, so the wash sale rule has no state effect there. The consequence to know is that your federal treatment still applies no matter where you live. What you should do is confirm your own state’s conformity on your state revenue agency’s site, because a handful of states adjust federal income in ways that can shift the timing.

Three Common Wash Sale Scenarios

Below are the three situations that catch most investors, each shown as what you did and what it costs you.

Scenario 1: Rebuying in a Taxable Account

What You Did	What It Costs You
Sold 100 shares at a $1,000 loss, rebought 100 shares 10 days later in the same brokerage account	Loss disallowed now, but the full $1,000 is added to the new shares’ basis and recovered when you sell them

This is the standard, recoverable case. The loss is only delayed, not lost. The consequence is a higher tax bill this year and a lower one later.

Scenario 2: Rebuying in an IRA

What You Did	What It Costs You
Sold 100 shares at a $1,000 loss in a taxable account, rebought the same stock in your Roth IRA within 30 days	Loss permanently disallowed under Rev. Rul. 2008-5, with no basis adjustment — the $1,000 is gone forever

This is the trap to fear. There is no future event that returns the loss. The consequence is total and final.

Scenario 3: Misreporting the Loss

What You Did	What It Costs You
Ignored the 1099-B wash sale flag and claimed the full loss, underpaying tax by $1,100	Repay the $1,100, plus a 20% accuracy-related penalty of $220 under IRC 6662, plus interest

This is the only version with an actual IRS penalty. The consequence is the tax, the fine, and growing interest.

Real-World Examples

Maria the Year-End Harvester

Maria sells 200 shares of a tech stock on December 20, 2025, locking in a $3,000 loss to offset gains. On January 5, 2026, she rebuys 200 shares because she still believes in the company. That repurchase falls inside the 30-day-after window, so her $3,000 loss is disallowed for 2025. The loss is added to her new shares’ basis, so Maria recovers it when she eventually sells — but her 2025 tax bill is higher than she planned because the offset disappeared.

David and the IRA Mistake

David sells a fund in his taxable account at a $4,000 loss on March 1, 2026. Two weeks later his IRA’s automatic investment buys the same fund. Because Rev. Rul. 2008-5 treats this as a wash sale with no basis bump in the IRA, David’s $4,000 loss is gone permanently. He cannot use it this year or any year. One automated purchase erased a real $4,000 deduction.

The Chen Household

Lisa Chen sells stock at a $2,000 loss in her account. Her husband, unaware, buys the same stock in his account 12 days later. Because the IRS treats a married couple as a single taxpayer for the wash sale rule, Lisa’s loss is disallowed even though he made the purchase. The Chens learn the rule looks across both spouses’ accounts, and they start coordinating loss sales.

Does the Wash Sale Rule Apply to Crypto in 2026?

For tax year 2025 and into 2026, the wash sale rule generally does not apply to cryptocurrency. The IRS treats crypto as property, not a security, and Section 1091 only covers “stock or securities.” So today you can sell Bitcoin at a loss, rebuy it minutes later, and still claim the loss.

This is a major, time-limited advantage for crypto holders, and it is also unsettled. Lawmakers have repeatedly proposed extending the wash sale rule to digital assets, and legislation discussed in 2026 could close this gap. As of June 2026, no such change has been finalized into law. The consequence of assuming the loophole is permanent is real risk: a new law could take effect quickly. What you should do is harvest crypto losses while the rule allows it, but watch for legislation and confirm the law before relying on it for a future year.

It is also worth noting that new Form 1099-DA crypto reporting starting in the 2025 tax year has caused confusion, with some brokers’ boxes hinting at wash sales. That reporting does not by itself make the wash sale rule apply to crypto for 2026.

Mistakes to Avoid

Ignoring the 30 days before the sale. A purchase you made before selling at a loss still triggers the rule, and the loss is disallowed.
Rebuying in an IRA. This converts a delayed loss into a permanent one with no basis recovery.
Forgetting your spouse’s trades. A married couple is one taxpayer for this rule, so a spouse’s purchase disallows your loss.
Overlooking dividend reinvestment. Automatic DRIP purchases of the same fund inside the window quietly trigger small wash sales and disallow part of your loss.
Ignoring RSU and ESPP vesting. Automatic share grants can trigger a wash sale if you sold the same stock at a loss within 30 days, disallowing the loss.
Skipping code W on Form 8949. Leaving it off creates a mismatch with your 1099-B and invites an IRS notice.
Claiming the disallowed loss anyway. This underpays your tax and exposes you to a 20% accuracy-related penalty plus interest.
Forgetting to track the adjusted basis. If you do not record the higher basis on your replacement shares, you overpay tax when you finally sell them.
Assuming two index funds are “different enough.” Some are substantially identical, and the IRS can disallow the loss anyway.

Do’s and Don’ts

Do’s

Do wait 31 days before rebuying the same security, because that clears the entire window and preserves your loss.
Do buy a non-identical replacement to stay invested, since a different company or different index keeps you in the market without a wash sale.
Do report every flagged wash sale on Form 8949, because matching your 1099-B avoids penalties.
Do track your adjusted basis and holding period, since both carry over and protect you from overpaying later.
Do coordinate with your spouse, because the rule combines both of your accounts.

Don’ts

Don’t rebuy a loss stock in any IRA, because the loss becomes permanent with no recovery.
Don’t rely on the 30-day count one way, since the window runs both before and after the sale.
Don’t assume crypto is forever exempt, because pending law could change it.
Don’t ignore automatic purchases from DRIPs, RSUs, or recurring buys, as they silently trigger the rule.
Don’t claim a disallowed loss to lower your bill, because the 20% penalty and interest cost more than the deferral.

Pros and Cons of the Wash Sale Rule

Pros

It only delays most losses, so in a taxable account you still get the full benefit later through a higher basis.
The holding period carries over, which can push your replacement shares toward lower long-term rates faster.
It is clear when you avoid it, because a 31-day wait or a non-identical replacement sidesteps it cleanly.
No fine for the wash sale itself, since the only cost is timing unless you misreport.
It still lets you stay invested, because you can buy a similar but not identical security right away.

Cons

It blocks aggressive tax-loss harvesting, so you cannot sell and instantly rebuy the same stock for the write-off.
The IRA version is permanent, which can erase a real loss with no recovery.
“Substantially identical” is vague, leaving investors to guess and risk disallowance.
It catches accidental triggers, like spousal trades and automatic reinvestments.
Misreporting adds a 20% penalty, turning a timing issue into a real cash cost.

What to Do Next

Pull your 1099-B for tax year 2025 and find every “wash sale loss disallowed” amount your broker flagged.
List each wash sale on Form 8949 with code W in column (f) and the disallowed amount in column (g), then carry totals to Schedule D before the April 15, 2026 deadline.
Record the adjusted basis of your replacement shares so you recover the loss when you sell them.
Check your IRA and spouse’s accounts for any repurchases inside the 61-day window, since those change the result.
Confirm your state’s conformity on your state revenue agency’s website.
Call a CPA or tax attorney if you have many trades, partial wash sales, an IRA repurchase, or a large disallowed loss — a professional review usually costs a few hundred dollars and can prevent a far larger penalty.

This article is educational and is not a substitute for advice from a licensed tax professional about your specific situation.

FAQs

Is a wash sale illegal?

No. A wash sale is not illegal and carries no fine by itself. For tax year 2025, the only consequence is that your loss is disallowed for now and shifted to the basis of your replacement shares — unless you misreport it.

What is the penalty for a wash sale?

There is none directly. The “penalty” is loss disallowance: you cannot claim the loss this year. In a taxable account the loss moves to your new shares’ basis and is recovered later, so it is a deferral, not a fine.

How long do I have to wait to avoid a wash sale?

31 days. Wait at least 31 days after selling at a loss before rebuying a substantially identical security. The window covers 30 days before and 30 days after the sale, so 31 days clears it.

Does the wash sale rule apply to crypto in 2026?

No. For 2026, the rule generally does not apply to cryptocurrency because the IRS treats crypto as property, not a security. Pending legislation could change this, so confirm the law before relying on it.

What happens if a wash sale occurs in my IRA?

The loss is permanent. Under Revenue Ruling 2008-5, a wash sale tied to an IRA repurchase disallows the loss and does not increase the IRA’s basis. The loss is gone forever, with no future recovery.

Can I claim a wash sale loss later?

Yes, in a taxable account. The disallowed loss is added to the cost basis of your replacement shares. When you sell those shares, the higher basis reduces your gain, so you recover the full loss then.

Are two different index funds substantially identical?

Usually not. Funds tracking the same index but issued by different companies are generally treated as not substantially identical. Still, the IRS gives no firm definition, so choosing a different index is the safest move.

Do wash sale rules apply to my spouse’s account?

Yes. The IRS treats a married couple as one taxpayer for this rule. A purchase in your spouse’s account within the window can disallow your loss, even if you did not buy the shares yourself.

How do I report a wash sale on my tax return?

On Form 8949. List the sale, enter code W in column (f), and put the disallowed loss as a positive adjustment in column (g). Then carry the totals to Schedule D with your 2025 Form 1040.

Can the IRS fine me over a wash sale?

Only if you misreport it. Claiming a disallowed loss and underpaying tax can trigger a 20% accuracy-related penalty under IRC 6662, plus interest. The wash sale itself carries no penalty.

Does selling at a loss and rebuying a call option count?

Yes. Acquiring a contract or option to buy substantially identical stock within the window triggers the rule. The loss is disallowed just as if you had rebought the shares directly.

What if I only rebuy some of the shares I sold?

Only that portion is disallowed. If you sold 100 shares at a loss but rebought 40 within the window, only the loss on 40 shares is disallowed. The rest of the loss stays deductible this year.

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