The IRS should not have assessed the additional tax liability without providing you or your representative the opportunity to present supporting documentation or additional information.
If the auditor proceeded as you described, you should appeal the results of the audit as soon as possible. Failure to appeal or file a tax court petition within the prescribed time limit (usually 30 and 90 days) may result in you losing your rights to an appeal prior to the final assessment of the tax liability.
Best regards,
Adam Brewer, Esq.
AB Tax Law
1-888-351-3707
Answered on Mar 15th, 2014 at 9:26 PM