What exactly needs to be attached to 8453? Your mailing instructions indicate the 1099 may not need to be attached but your filing instructions says it does

[gnckraft]

Your mailing instructions during entry indicate that you do not need to attach a copy of the 1099-B if the summary includes only Box A & D sales.

[AnthonyC · Accepted solution]

In limited situations, you’re allowed to summarize investment sales without providing complete details.  If you are summarizing multiple investment sales that are either Box A sales or Box D sales, and there are no adjustments necessary (i.e. Code W for wash sales or adjustments to basis), then it is not necessary to mail in a statement with further details.  Turbotax will tell you this when your sales meet the criteria and will not prompt you to mail any statements.

So, if you are being prompted to mail further statements after filing, then you have adjustments to your sales and you should follow the mailing instructions and include your 1099-B statements with Form 8453.

[mercurynfo]

Just add the need to attach 1099s to the mailing instructions so we don't have to hunt down the answer to this question.