@jennyw22 correct, that's exact question i had , for wash sales to be accurate they need to go back to find 'buy cost basis' going back years depending when it was bought. csv file mostly include only current years data. If he asks you csv file of lets say from couple of years and uses his software to get that info, it may be fine. Other option for him is to look into 1099B to get that info.
In the end, your numbers should match up with 1099B summary!
