yes fifo.
the sale on 1/10/19 would be those acquired 1/1/18. resulting in a loss of $400. the replacement shares would be those bought on 1/1/19 resulting in a basis of $900 - $500 paid + the $400 wash sale
the holding period tacks on so the acquisition date for these shares is 1/1/18
the 2/10 sale would be those that now have a 1/1/18 acquisition date so now there is a $300 loss - $600 selling price vs $900 adjusted basis due to previous wash sale
the replacement shares would be those purchased 1/25/19 which now have a basis of $800 - $500 paid + $300 wash sale and again the holding period would tack on so these shares would be deemed acquired 1/1/18
wash sales can become nightmares because if you were to sell at a loss in a taxable a/c and then within that 61 day window buy shares in an IRA a/c there would be a wash sale. but that loss does not tack on to the IRA shares so it's lost forever.
