You sell a losing position in your taxable brokerage account in November, book the loss, and move on. Three weeks later, in a completely different app, your IRA's auto-invest feature buys the same stock back as part of a scheduled rebalance you set up months ago and forgot about. Nothing about that second trade looks like tax planning — it's not even in the same account, and you probably didn't think of it as the "same position" at all. The IRS does. The wash sale rule tracks the same or substantially identical security by CUSIP across every account you own, taxable and retirement combined, and a loss harvested in one place can be silently disallowed by a trade placed days later in an account most traders never think to check.
The window is 61 days, and it isn't just "after"
The rule everyone half-remembers is "don't buy it back for 30 days." The actual window is longer and runs in both directions: 30 days before the sale, the day of the sale, and 30 days after — 61 calendar days in total, not trading days. A buy inside that window, on either side, in the same or a substantially identical security, disallows the loss.
The 61-day window around a loss sale
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1
30 days before the sale (Day -30)
A purchase here can retroactively tie up a loss you haven't realized yet — the window doesn't start counting at the sale date, it's centered on it.
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2
The loss is realized (Day 0)
You sell at a loss. Nothing is disallowed yet on its own — what happens on either side of this date is what decides that.
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3
30 days after the sale (Day +30)
A buy here, in any account you own, in the same or a substantially identical security, disallows the loss.
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4
The full window: 61 days
Day -30 through Day +30 around the sale date. Calendar days, counted straight through weekends and holidays.
That "any account you own" part is where the rule stops matching how most people actually track their trades. You watch your taxable brokerage because that's where the red number showed up. The IRS doesn't care which statement the replacement purchase appears on — it cares whether you, the taxpayer, ended up holding the same exposure again inside the window.
"Substantially identical" is narrower — and sometimes wider — than you'd guess
The rule doesn't just cover buying back the exact same ticker. It covers anything the IRS treats as substantially identical, which is a legal standard, not a plain-English one, and it doesn't line up neatly with what feels like "the same trade."
What counts as substantially identical
| What you bought back | Same CUSIP as what you sold? | Substantially identical? |
|---|---|---|
| Same ticker, same share class | Yes | Yes — the textbook case |
| Same company, different share class (e.g. voting vs. non-voting shares) | No | Usually not — different CUSIPs, and the IRS hasn't generally treated these as identical |
| Call options on the stock you sold | No | Often yes in practice — the IRS and courts have treated options as potentially substantially identical to the underlying |
| A different ETF tracking the same index as the one you sold | No | Generally not — different fund, different CUSIP, even with identical holdings |
| The same stock, repurchased inside your IRA instead of your taxable account | Yes | Yes — and the consequence is worse here, not the same (more on that below) |
That last row is the one that matters most for a day trader running positions across more than one account, because it isn't really a question about what you bought back — it's the same stock either way. It's a question about where, and that changes what the disallowed loss actually costs you.
In your own taxable account, a wash sale is deferred. In an IRA, it's gone
This is the distinction most explanations skip, and it's the reason the IRA version of this mistake is worse than the plain-vanilla version — not just as bad.
Same wash sale, two different outcomes
Repurchased in the same taxable account
The loss is disallowed for now. It isn't gone.
- The disallowed loss gets added to the cost basis of the replacement shares
- You recover the benefit later — when you eventually sell the replacement shares for good, that higher basis reduces the gain (or increases the loss) you report then
- The holding period of the original shares also carries over, so it isn't pure cosmetics
Repurchased inside an IRA
The loss is disallowed permanently. There's nothing left to adjust.
- An IRA doesn't track cost basis the way a taxable account does, so there's no basis to add the disallowed loss to
- Per IRS Revenue Ruling 2008-5, the loss is gone outright, not deferred into a future sale
- This applies whether it's a traditional IRA, a Roth IRA, or technically a spouse's IRA on a joint return
The mechanism that normally makes a wash sale a timing problem instead of a real loss — the basis bump on the replacement shares — only works in an account that tracks basis in the first place. An IRA doesn't, so the adjustment has nowhere to go. The loss doesn't come back later. It just stops existing for tax purposes.
A loss isn't worth its full face value to begin with — it's worth your marginal tax rate applied to it — which is what the IRA version of this actually costs you.
What a disallowed loss is actually worth, by outcome
The everyday version of this doesn't need a second account at all
Active day traders trip this rule constantly with no IRA anywhere near it, because the rule doesn't ask whether the repurchase was deliberate tax planning or just the next trade in your normal rotation. Sell a stock for a loss on Monday, and if your scan puts the same name back on your watchlist Thursday and you take it, buying it again in the exact same taxable account — no cross-account confusion involved — is still a wash sale. For someone trading the same handful of liquid names every week, that can mean a real share of a year's realized losses get disallowed and carried into per-lot basis adjustments that are tedious to track by hand.
That version of the problem has an actual off-switch for traders who qualify: electing mark-to-market accounting under Section 475(f). A trader who makes that election treats every open position as sold at year-end for tax purposes and reports trading gains and losses as ordinary income instead of capital gains — and the wash sale rule doesn't apply to mark-to-market traders at all. It isn't a free pass; it has its own eligibility test, and it trades away the lower long-term capital gains rate on anything you'd otherwise have held a year. It's a decision to make with a tax preparer, not mid-session. But it's worth knowing the rule has a real exit for traders who qualify, rather than assuming every active trader is stuck hand-tracking wash sales forever.
Why the cross-account version keeps happening without anyone deciding to break the rule
Nobody sits down and plans to violate the wash sale rule across accounts on purpose — it happens because the accounts don't talk to each other and the trader doesn't either. A taxable brokerage statement doesn't show your IRA's holdings. Your IRA's dividend reinvestment or auto-rebalance doesn't ask whether you sold the same stock for a loss somewhere else three weeks ago. Each account, viewed on its own, looks completely clean. The violation only exists at the level of you as a taxpayer, which is exactly the level none of your individual account dashboards are built to show you.
A spouse's accounts add the same blind spot on a joint return. The IRS has disallowed losses where one spouse sold at a loss and the other bought the same position back shortly after in an account that, as far as either of them individually was concerned, had nothing to do with the sale.
What to actually check before you harvest a loss
None of this is a reason to avoid tax-loss harvesting — a legitimate loss is still worth taking. It's a reason to check the right scope before you do, which is wider than "my trading account" for almost everyone who holds a retirement account alongside it.
Before you sell for a tax loss
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You listed every account that could hold the position — Taxable brokerage, IRA, Roth IRA, and a spouse's versions of each if you file jointly. If any of them has auto-invest or dividend reinvestment turned on, add it to the list even if you didn't place the trade yourself.
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You counted the full 61 days, not just the 30 after — A purchase up to 30 days before the sale counts too. If you've been accumulating the same name over time, check what you bought in the month leading up to the loss, not just what you might buy after.
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You know whether your replacement trade could be "substantially identical" — A different ticker on the same company, or an options position on the stock you just sold, isn't automatically safe. When it's close, treat it as a wash sale until you've confirmed otherwise.
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You're assuming the rule only sees the account where the loss showed up — It doesn't. The IRS is checking you, across every account, not the one statement that happens to have the red number on it.
That same discipline — deciding up front what you'll check before you act, instead of reconstructing it after the fact — is the same habit a trading plan is supposed to force on the entry side. If you already write down your stop and your size before you're in a trade, add one more line for a loss you're planning to harvest near year-end: which accounts, and whose, you'll check first.
The bottom line
The wash sale rule isn't an IRA rule or a brokerage-account rule — it's a rule about you, checked across everything you hold, taxable and retirement combined. A loss sold cleanly in one account can be undone by a trade you didn't even think of as related, placed in an account you weren't looking at. Checking that scope costs a few minutes before you sell. Finding out about it in April costs the deduction, and if the replacement landed in an IRA, it costs it for good. None of this touches whether the trade itself was a good idea — getting the setup right and getting the account right are two separate checks, and only one of them shows up on a chart.
