Taxes. Nobody loves them, everybody has to pay them. It is hard enough having to pay all your taxes as a regular citizen, but if you are a business owner it goes to a completely new level of difficulty.
Large businesses may have departments handling accounting and tax, so that the CEO can focus on growing and improving the company. If you are a small business owner, chances are you start April of every year frustrated at the number of lines on your tax form.
Overpaying taxes can actually be one of many errors businesses can make. The US tax code is notoriously complex and each state has different laws. Opening up shop or doing business in a high-tax state can load up the expense line.