you may have imported into the wrong sales category.
since you have no 1099-B you should be reporting under category C or F.
If Turbotax is forcing you to summarize, it is doing you a disservice since 400 is below the advertised capacity of Turbotax Online.
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IRS requires details to be listed on Form 8949,
or on your own forms (e.g. csv spreadsheets) which have the same information and in the same manner as Form 8949.
Either way, if you choose to summarize, you have to mail the transaction details to the IRS within three business days of IRS accepting your tax return.
Exception: transactions in category A or D without adjustments do not require form 8949. No mailing is necessary.
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