For the tax authorities, catering and gastronomy businesses are considered as risk industries. In case of an external inspection according to § 193 AO (German general tax code), business owners should be prepared for the fact that tax auditors, specialized on catering and gastronomy businesses, will review all business documents for irregularities. The auditors are armed with various guidelines and key figures as well as special testing software (IDEA). If there are gaps in their bookkeeping or serious shortcomings, the exam is quickly over and the tax office is entitled to estimate profits. Since a tax audit generally takes place retroactively for up to three years, the total back payments for sales, income tax and, payroll taxes and social security contributions can quickly add up to a six-figured amounts.