Wash Sale Rule Calculator
Check if a stock repurchase triggers the wash sale rule. See adjusted cost basis.
By Konstantin Iakovlev · Updated April 2026 · Source: SEC
Wash Sale Triggered?
Yes
Disallowed Loss
$5,000.00
Adjusted Basis
$14,500.00
Wash Sale Analysis
| Days Between Sale and Repurchase | 10 days |
| Within 30-Day Window? | Yes — wash sale applies |
| Total Loss on Sale | $5,000.00 |
| Disallowed Loss | $5,000.00 |
| Currently Deductible Loss | $0.00 |
Adjusted Cost Basis
| Original Basis Per Share | $95.00 |
| Disallowed Loss Added | $50.00 |
| Adjusted Basis Per Share | $145.00 |
Alternative Strategies
| Wait 31+ days | Repurchase after wash sale window |
| Buy similar (not identical) fund | E.g., switch S&P 500 ETFs from SPY to VOO |
| Double up | Buy first, wait 31 days, then sell original |
| Harvest in tax-advantaged account | Buy replacement in IRA (different rules apply) |
Use the Wash Sale Rule Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.
Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.
How It Works
Selling a stock at a loss feels like a clean way to harvest a tax benefit, but the IRS Wash Sale Rule can quietly disallow that capital loss and reshape your adjusted cost basis. This tool maps out whether your repurchase falls into the trap, so your 2026 tax reporting reflects what the IRS will actually accept rather than what you hoped to claim.
The trigger is mechanical: sell a security at a loss, then buy substantially identical stock within 30 days before or after the sale, and you land inside a 61-day window that voids the deduction. When that happens, the disallowed loss isn't gone forever. It rolls into the cost basis of the replacement shares, raising that basis by exactly the amount you couldn't deduct.
Many investors track only the exact ticker and miss the wider net the rule casts. Options and ETFs that follow the same underlying asset count as substantially identical, and the rule reaches across accounts, so a repurchase in your IRA can spoil a loss booked in your taxable brokerage. Treat the position, not the symbol, as what you're really watching.
Example: Wash Sale Impact
- 1 Input: You sold 100 shares of XYZ Corp. on April 1, 2026, at $50 per share, realizing a $500 loss (original cost basis was $55 per share). You then repurchase 100 shares of XYZ Corp. on April 15, 2026, at $52 per share.
- 2 Calculation: Since the repurchase occurred within 30 days of the sale at a loss, a wash sale is triggered. The $500 loss is disallowed. This $500 is added to the cost basis of your newly acquired shares.
- 3 Result: Your adjusted cost basis for the 100 shares purchased on April 15, 2026, is $5,700 ($5,200 purchase price + $500 disallowed loss). Your per-share adjusted cost basis is $57.00.
- 4 Context: You cannot claim the $500 loss on your 2026 tax return. Instead, it effectively reduces any future capital gains or increases any future capital losses when you eventually sell the repurchased shares, due to the higher cost basis.
Source: SEC · Last updated: April 2026
Frequently Asked Questions
What is the wash sale rule? (detailed)
Does the wash sale rule apply to crypto?
Can I buy a similar ETF to avoid a wash sale?
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