There is no IRS form associated with the sales tax
entry. There are worksheets found in Publication 600.
preparer may have used a separate worksheet and not provided it to you with your return.
Ultimately, to satisfy an IRS audit letter, you will need physical receipts for purchases, and an itemized spreadsheet accounting for those receipts.
The specificity with which the entry appears to be made, suggests that either the tax preparer had receipts from you as a basis for the total, or that he/she was committing a bit of tax fraud on your behalf. In the former case, he/she ought to be able to produce the supporting documentation. And, in either case, failure to do so would be malpractice and you could sue the tax preparer for any penalties and interest that you sustain as a result of the tax preparer's breach of the duty of care to you in the preparation
of the tax return.
Hope this helps.
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