Wash sale

A wash sale usually postpones your loss. Section 1091 of the tax code disallows the loss now and adds it to the cost basis of the new shares. The time you held the old shares carries over to the new ones. When you sell the new shares, the higher basis gives you a smaller gain or a larger loss.

Counting the day of the sale, the window is 61 days. A contract or option to buy counts as a purchase. Your broker reports wash sales only for identical securities in the same account. A purchase in another of your accounts still counts, and so does one by your spouse or a corporation you control. You have to catch these yourself. An ESPP purchase of employer stock inside the window can also turn a loss sale into a wash sale. No statute or IRS guidance says whether shares you receive when RSUs vest count as a purchase.

The costliest case is buying the stock back in your IRA or Roth IRA. The loss is still disallowed, and the IRA gets no basis for it, so the loss is gone for good.

The IRS treats crypto as property, not as stock or a security. Under current law, the rule does not reach crypto you hold directly. Shares of a crypto fund taxed as a corporation are securities, so the rule covers them. For spot ETFs set up as grantor trusts, the answer is unsettled. A bill now in Congress could extend the rule to crypto.