The guide advises that the first step in the investigation of a business is to consult the Central Registration Section in Baltimore, which is the hub of the State's business files. Each business operating in compliance with Maryland law will have in these records a Combined Registration Application. This form is used to apply for a Sales and Use Tax license. It can also be used to open Income Tax Withholding Accounts and Unemployment Insurance Accounts for employees. Unless the business has no employees and is not collecting sales tax, it should have a Combined Registration Application on file, or it is violating Maryland law. Following a review of the Maryland penalty for failure to file retail sales tax and withholding tax, the guide describes the State agencies and other State resources that can be used in the investigation of a business operating in Maryland. Federal, county, and miscellaneous resources for information on a business operating in Maryland are also profiled. Business information to be found in libraries and various computerized databases is discussed as well. Subject index