Wash Sale Calculator
Calculate wash sale disallowed losses and adjusted cost basis. Understand the 30-day rule, substantially identical securities, and strategies to avoid wash sale violations.
Transaction History
Enter sell (with loss) and buy transactions. Include date, type, shares, and prices.
Wash Sale Rule
If you sell stock at a loss and buy the same or substantially identical stock within 30 days before or after the sale, the loss is disallowed. The disallowed loss is added to the cost basis of the repurchased shares.
Window:30 days BEFORE + 30 days AFTER
Result:Loss disallowed, added to basis
Wash Sale Analysis
| Sell Date | Buy Date | Days | Original Loss | Disallowed | Allowed | Wash Sale? |
|---|---|---|---|---|---|---|
| 2024-01-15 | 2024-01-25 | 10 | $1000.00 | $1000.00 | $0.00 | YES |
Disallowed Loss Summary
$1000.00
Allowed Loss:$0.00
Adjusted Basis Added:$1000.00
Disallowed losses are NOT lost forever - they're added to repurchased stock's cost basis, reducing future taxable gain.
Adjusted Cost Basis Detail
Original Purchase Cost:$4600.00
Disallowed Loss Added:$1000.00
New Adjusted Basis:$5600.00
Future Gain Reduction:$1000.00
When you sell the repurchased stock, higher basis = lower taxable gain = tax benefit recovered.
Tax Impact Analysis
Tax Benefit Lost Now:$350.00
Future Tax Benefit:$150.00
Net Tax Impact:$200.00
Net impact depends on rates. Disallowed loss saved at ST rate (~35%), future benefit at LT rate (~15%) = net cost.
Strategies to Avoid Wash Sale
- Wait 31+ days before repurchasing same stock
- Buy different but similar stock (e.g., sell S&P 500, buy Total Market)
- Buy in different account (IRA) - IRS says wash sale applies across ALL accounts
- Wait 31+ days AFTER repurchase to sell (30-day rule also applies BEFORE)
- Sell and buy substantially different security
- Use ETF alternatives (sell VOO, buy SPY is NOT allowed - too similar)
What's "Substantially Identical"
- Same stock/CUSIP number = identical
- Options on same stock = identical
- ETF tracking same index = likely identical
- Mutual fund vs ETF tracking same index = gray area, risky
- Different index (S&P 500 vs Total Market) = NOT identical
- Preferred vs common stock of same company = gray area
Wash Sale Technical Rules
- 30-Day Window: Applies 30 days BEFORE and 30 days AFTER the loss sale date. Total 61-day window.
- Same Security: Same CUSIP number, stock ticker, or substantially identical security triggers wash sale.
- All Accounts: Wash sale applies across ALL accounts - taxable, IRA, Roth IRA, spouse's accounts. IRS tracks by security, not account.
- Partial Purchases: If buy 50 shares and sold 100 at loss, 50% of loss disallowed. Match shares bought to shares sold.
- Disallowed Amount: Entire loss on matched shares is disallowed. Added to NEW shares' cost basis.
- Deferred Benefit: Benefit recouped when NEW shares sold. Higher basis = lower gain. If sold at loss again, bigger loss.
- IRA Exception: Loss on taxable account, buy in IRA = loss permanently disallowed (no cost basis adjustment possible in IRA).
- Options/Contracts: Buying options on same stock counts as substantially identical. Selling options may trigger wash sale too.
Common Wash Sale Mistakes
- IRA Purchases: Many think buying in IRA avoids wash sale. NO - loss permanently disallowed with no basis adjustment.
- Different Brokerage: Think wash sale only applies at same broker. NO - IRS tracks across all accounts.
- Pre-Sale Purchase: Many forget the 30-day BEFORE rule. Buy on Dec 15, sell Dec 20 at loss = wash sale.
- Similar ETFs: Sell VOO (S&P 500), buy IVV (S&P 500) = likely wash sale. Different but substantially identical.
- Auto-Reinvest: Dividend reinvestment within 30 days of loss sale triggers wash sale on that portion.
- Broker Reports: 1099-B may NOT show wash sale adjustments. IRS expects you to self-report. Check transactions yourself.