What happens to a disallowed wash sale loss?

The disallowed loss is added to the cost basis of the repurchased substantially identical security (in a taxable account). This means the loss is not permanently lost — it is deferred until you eventually sell the repurchased security. However, if that future sale is at a long-term rate versus a current short-term benefit, or if the repurchased security also declines, the timing effect can be costly.

Does the wash sale rule apply across different account types?

Yes. The IRS applies wash sale rules across all accounts in which you hold substantially identical securities — including IRAs, Roth IRAs, and 401(k) accounts. Purchasing in a spouse’s account also triggers the rule for jointly-reported taxpayers. This makes loss harvesting near IRA contribution dates or in dual-account households particularly complex.

Can I automatically harvest losses with a robo-advisor and avoid wash sales?

Robo-advisors like Betterment and Wealthfront have sophisticated systems to avoid wash sales within the accounts they manage. However, they cannot see your other brokerage accounts. If you also hold investments in other taxable accounts or IRAs, the robo-advisor’s harvesting could unknowingly trigger wash sales from your other accounts. Coordinate all account holdings before relying on automated harvesting.

How do I document that I avoided a wash sale?

Your 1099-B from your broker should note wash sale adjustments. To document that you successfully avoided one: maintain records of the sale date, the replacement security purchased, its ticker or CUSIP (different from the sold security), and purchase date. The broker’s trade confirmations provide this documentation. If the IRS challenges, you need to demonstrate the replacement was not substantially identical.

Is there any way to harvest a loss and immediately reinvest without triggering the wash sale rule?

Yes — through the 'like but not substantially identical' approach: selling Vanguard S&P 500 (VOO) and buying Schwab US Broad Market (SCHB) or iShares Russell 1000 (IWB) maintains very similar market exposure without triggering the wash sale rule. These funds provide 95%+ correlation to the original holding while being definitively different securities tracking different indexes.

The Wash Sale Rule: How to Harvest Losses Without Getting Caught

The wash sale rule is the IRS mechanism that prevents investors from selling a security at a loss for a tax deduction and immediately buying it back — effectively buying a tax benefit without changing their investment position. Understanding exactly what triggers the rule (and what does not) is essential for executing tax-loss harvesting without losing the tax benefit.

What the Wash Sale Rule Prohibits

The wash sale rule (IRC Section 1091) disallows a loss deduction when you sell a security at a loss and acquire a 'substantially identical' security within 30 days before or after the sale. The disallowed loss is not permanently lost — it is added to the cost basis of the repurchased security. However, this delays the deduction potentially for years.

Wash sale rule trigger examples

Action	Wash Sale Triggered?	Explanation
Sell VOO (Vanguard S&P 500 ETF) at loss, buy SPY (iShares S&P 500 ETF) same day	Likely yes	Same index = substantially identical
Sell VOO at loss, buy VTI (Vanguard Total Market) same day	No	Different index, different holdings
Sell Apple stock at loss, buy Apple stock 25 days later	Yes	Same security within 30-day window
Sell Apple stock at loss, buy Apple stock 35 days later	No	Outside the 30-day window
Sell bond fund at loss, buy similar bond fund from different provider	Depends	If bond funds track same index: likely yes
Sell stock at loss, buy call options on same stock	Yes	Options on substantially identical security trigger rule

What Counts as 'Substantially Identical'?

The IRS has not provided comprehensive guidance on exactly what is substantially identical beyond individual stocks. For mutual funds and ETFs, general guidance: funds tracking the exact same index are likely substantially identical. Funds tracking different indexes of similar asset classes (S&P 500 vs total market) are generally not substantially identical. Different companies' funds tracking different indexes in the same category are the safest replacement choices.

Identical securities: Same fund, same company, same share class — always a wash sale
Different providers, same index: VOO and IVV both track S&P 500 — likely substantially identical
Different index, same category: S&P 500 fund for total US market fund — generally not
Individual stock for sector ETF: Not substantially identical in most cases
Mutual fund for its ETF share class: Likely substantially identical
Short position for long position: Complex — consult a tax professional

⚠️Automatic Dividend Reinvestment Can Trigger Wash Sales

If you sell shares of a fund at a loss and your account automatically reinvests dividends from that fund within 30 days before or after the sale, the reinvestment triggers the wash sale rule. Disable automatic dividend reinvestment before harvesting losses from any fund, or switch dividends to a different fund temporarily.

The IRA Wash Sale Trap

If you sell a security in a taxable account at a loss and repurchase substantially identical securities in an IRA within the 30-day window, the wash sale rule applies — and the loss is permanently disallowed (not just deferred). Unlike a taxable repurchase where the loss is added to the new basis, an IRA purchase creates no mechanism to recover the disallowed loss. This is the most costly wash sale trap.

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The Wash Sale Rule: How to Harvest Losses Without Getting Caught

What the Wash Sale Rule Prohibits

What Counts as 'Substantially Identical'?

The IRA Wash Sale Trap

Frequently Asked Questions

Frequently Asked Questions

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