Small businesses often get in trouble over payroll taxes and borrowing from trust fund taxes, says Michael Savage, a 30-year tax law veteran and author of Don't Let the IRS Destroy Your Small Business: 76 Mistakes to Avoid. "[Small-business owners] see that large chunk of withheld social security and income taxes sitting in their accounts for anywhere from a few days to a couple of weeks before it gets sent in to the IRS, and they've got bills to pay. So they say, 'Well, I'll just use that money to pay the bills. When it comes time to send it into the IRS, I'll have some more money in and then I'll send it in.' And of course, when it comes time to send it in to the IRS, they don't have it.

"The one thing the IRS makes very sure of and audits very carefully is the payment of trust fund taxes. And what many small businesspeople don't realize is that they're personally liable for those taxes, even if their company is a corporation. They, as the owners or as the COOs of the corporation, have personal responsibility to get those trust fund taxes paid. And if they don't, the IRS can come take their home and their car and their kids' college education money and anything else to get those taxes paid."