Thank you. 

The letter states they "couldn't verify the total federal withholding amount".  The taxpayer has several W-2s but only one from a small business with the exact $1800 withholding amount in question.  The W-2 was prepared by a payroll company, and the withholding was only 8% of wages so not large.  

If I'm sending letter requesting "a small dollar case appeal" as the letter directs, with evidence, do I still add wording: if the IRS does not agree you are entitled to the additional refund, that they forward your request to the IRS Independent Office of Appeals (Appeals)?

Also, should I send summary of all W-2 and withholdings even though it's obvious this is the culprit? 

Thanks