The wash sale rules apply when you sell a stock or a security at a loss and then repurchase the same stock or a substantially identical stock within 30 days before or after the sale. Under these rules:
b) Not recognized at time of sale and does not affect basis of newly acquired stock. This means that if you trigger a wash sale, the loss you realize from the sale is not recognized for tax purposes at that time. Instead, that loss is disallowed and is added to the basis of the stock that you repurchased, effectively deferring the loss until you sell the newly acquired stock in a transaction that does not trigger the wash sale rule.