Wash Sale Risk Checker

The checker starts with the loss sale. If the sale does not produce a loss, there is no wash-sale loss to disallow. If there is a loss, it calculates loss per share and builds the 61-day review period: 30 days before the sale, the sale date, and 30 days after the sale.

It then tests replacement lots against that window and the selected substantial-identity assumption. Matching replacement shares are capped at the number of shares sold, so a partial rebuy only disallows the matched portion of the loss. Taxable-account replacements show a potential basis adjustment, while IRA, spouse, controlled corporation, and option cases are flagged separately for review.

The result is a filing-prep estimate. Use it before relying on a harvested loss, before importing broker data into tax software, or when one broker did not see activity in another account.

The wash-sale window is 61 days, not just 30 days after the sale

Many investors only check whether they bought back the position after a loss sale. The IRS rule is wider. It looks at the period beginning 30 days before the sale and ending 30 days after the sale. That means a pre-sale purchase, an automatic dividend reinvestment, or a replacement purchase in another account can affect the loss.

The checker displays the start date, end date, and a standard next-day repurchase date. That date is not a portfolio recommendation. It is simply a timing reference for the wash-sale window around the sale entered in the tool.

Wash-sale risk depends on both timing and replacement identity

Partial replacements create partial disallowed losses

If you sell 100 shares at a $3,000 loss and buy 40 substantially identical shares inside the window, the checker allocates loss per share to 40 matched shares. The remaining 60-share portion may still be deductible before the usual capital-loss netting rules, assuming no other replacement lots apply.

That allocation matters because broker summaries can hide lot-level details. A household with multiple brokers, dividend reinvestment, and option trades can easily create a different wash-sale result than one line on one Form 1099-B suggests.

Taxable-account wash sales usually defer the loss into replacement basis

In a standard taxable-account wash sale, the loss is not currently deductible. Instead, the disallowed loss is generally added to the basis of the replacement shares. That means the loss may be recovered later when the replacement shares are sold, assuming the later sale is not itself affected by another wash sale.

Pair this checker with the Stock Loss Tax Calculator after you decide which losses are actually deductible this year.

IRA and Roth IRA replacements are the highest-severity review case

A taxable brokerage loss followed by a substantially identical IRA or Roth IRA purchase inside the window can be worse than an ordinary taxable-account wash sale. IRS Revenue Ruling 2008-5 says the loss is disallowed and the basis of the IRA or Roth IRA is not increased by that disallowed loss.

This is why the checker separates IRA/Roth IRA risk from normal taxable-account basis adjustments. A broker may not consolidate retirement-account activity with the taxable account that produced the loss.

ETFs, mutual funds, and options need substantial-identity support

The term substantially identical is not a simple ticker-similarity test. Two securities can be economically similar without necessarily being substantially identical, and some instruments can be close enough to require review. For ETFs and mutual funds, look at index, issuer, objective, holdings, and strategy. For options and convertible securities, review contract terms, strike, expiration, conversion rights, and the underlying security.

The checker treats a similar ETF or fund as a review case. It is designed to stop a premature deduction, not to certify that a substitute fund is safe.

Crypto and digital assets need a separate workflow

IRS digital asset guidance treats digital assets as property and requires reporting of sales, exchanges, and other dispositions. This checker does not automatically apply the classic stock/securities wash-sale rule to ordinary crypto or NFT lots. However, tokenized securities, broker-reported Form 1099-DA fields, economic substance, and future law changes can still matter.

Use the Crypto 1099-DA Tax Calculator and the NFT/Digital Asset Cost Basis Calculator for digital-asset basis and 1099-DA reconciliation after this wash-sale review.

Form 8949 code W is a reconciliation step, not the whole analysis

IRS Form 8949 instructions use code W when there is a nondeductible wash-sale loss and put the adjustment amount in column (g). But the form entry only follows the analysis. You still need to know which lot was sold, which replacement lots were acquired, whether the replacement was substantially identical, and whether a broker-reported amount is incomplete because activity occurred in another account.

Keep the broker statement, replacement trade confirmations, DRIP records, option confirmations, spouse or controlled-entity records, IRA activity, and any written substantial-identity memo with the return file.

Last reviewed: May 31, 2026. The checker uses public IRS guidance for Publication 550 wash sales, Form 8949 code W reporting, capital gains and losses, Revenue Ruling 2008-5 IRA treatment, and digital-asset reporting. It intentionally flags cross-account and substantially identical questions instead of treating broker output as final.

Keep the research moving with Stock Loss Tax Calculator, Capital Gains Tax Calculator, NFT/Digital Asset Cost Basis Calculator, and Crypto 1099-DA Tax Calculator.