IRS Pub 550, page 56 said this:elgob wrote: ↑Wed Mar 25, 2020 2:16 pmIt's unclear, it seems to me, that the highlighted point is relevant under the language of the statute, regs, or IRS Pub 550 (none of which, for example, refers to "replacement shares", or deals with a disposition of those previously purchased shares). Under the statutory language, it seems that you would have a wash sale on the number of VTSAX shares sold equal to the number of VTSAX shares bought in the preceding 30 days. I realize that most others in this thread take a different view, and they might well be right. I just haven't seen the authority to support it.
So even if there is a wash sale, the disallowed loss can be added to the shares bought within the past 30 days as additional basis. If the only remaining shares are in the IRA or Roth-IRA, well, since there is no concept of "basis" for IRA accounts, the loss is permanently disallowed. The "replacement shares" term is not used in any IRS publication of course, but thinking in those terms would clarify the application of wash-sale rules.If your loss was disallowed because of the wash sale rules, add the disallowed loss to the cost of the new stock or securities (except in (4) above). The result is your basis in the new stock or securities. This adjustment postpones the loss deduction until the disposition of the new stock or securities. Your holding period for the new stock or securities includes the holding period of the stock or securities sold.
Edit: well, iceport got to it first