Taxpayer worked as an independent contractor providing bulk mail delivery services to the United States Post Office. Taxpayer was not aware that he was required to report and pay gross receipts tax on his receipts from selling services. The Department assessed the Taxpayer for gross receipts tax, penalty and interest on these receipts. Taxpayer paid the assessment and then filed a claim for refund for the penalty and interest. The Department denied the claim and the Taxpayer filed a protest. Taxpayer disputed the Department’s assessment of penalty and interest because the Department, the Post Office and his accountant all failed to tell him of his tax liability. Held: It was the Taxpayer’s obligation to determine his tax liability to the state. The Taxpayer was negligent in failing to determine the tax consequences of engaging in business as an independent contractor, and penalty and interest is due on his underpaid gross receipts taxes. Protest Denied.