Wash sale calculator (US): disallowed loss and new basis
You sold at a loss, then bought back, or a put got assigned. Can you still claim the loss? Put in your dates and share counts to see what you claim now, what moves into the new shares, and when they turn long-term.
How it works: a loss is a wash sale when you buy the same or "substantially identical" stock in the 30 days before or the 30 days after you sell it. That's a 61-day window. An assigned put counts as a buy. Only the shares you bought back are matched: disallowed loss = loss per share × the smaller of (shares sold, replacement shares). The disallowed part is added to the cost basis of the replacement shares, and the days you held the old shares carry over to the new ones. In an IRA the loss can't be added to anything, so it's gone. Dates are trade dates. US rule as of October 2026 (IRS Publication 550). This page doesn't track spouses' accounts or several lots.
The loss isn't gone, it moves
In a taxable account, a wash sale delays the loss. It doesn't erase it. The cash you lost is the same. What changes is the year you can use it. Say you sold at a loss in November to cancel a gain from earlier in the year. A put you sold gets assigned three weeks later. The loss slides into the new shares' basis. Your gain this year is taxed in full. The loss waits until you sell the new shares, which may be next year or later. See taxes on selling options in the US.
Where the wheel trips it
In the wheel strategy you sell puts on stocks you like. So after a loss sale, the next move is often a new put on the same stock. That's the trap. If it's assigned inside the 30 days, you bought the shares back. Buying a call on the same stock can count too. The worst version is buying back in an IRA: that loss is lost for good. The clean fix is to wait 31 days, or sell the put on a different company. More in wash sales and options and IRA vs taxable accounts. In Canada the rule is different; use the superficial loss calculator.
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