Yes, this is true. When you have a wash sale, the disallowed loss is used to increase the cost basis of the "replacement shares" (shares that you bought within 30 days before or after the wash sale). This allows you to realize the benefit of the disallowed loss at a later date when you sell and don't have a wash sale. Suppose you bought some shares a week before you sold all of your shares for a loss. Even if you did consider this to be a wash sale because of the shares you bought a week before, adding the disallowed loss to the basis of the week-old shares would have the same effect as if you ignore the wash sale rule entirely.