Even for people not familiar with tax law, the term "tax evasion" is not a good thing. Indeed, most people would not know about the penalties that come with being convicted for federal tax evasion or failing to pay employment taxes (for employers). However, the threshold level fears can't be underestimated. The Internal Revenue Service can order an offending company to pay taxes and substantial penalties for non compliance with the tax code. These penalties can be fatal to a business, and leave a number of related principals liable as well.
A recent Forbes.com article explained how widespread the IRS' powers are as well as who can be held liable. Essentially, business owners and are routinely held liable and exceptions are rarely made. In one case, a business owner was held liable for failing to pay employment taxes even though he claimed that he was misled by his bookkeeper.
In another tax case, a business principal was held responsible for failing to pay employment taxes even though it was found that the company's accountant was embezzling money and passed away without filing taxes (or paying employment taxes).
The IRS can go even as far as assessing personal liability for unpaid employment taxes on all principals involved in a company. This is ostensibly done to make sure that offending owners don't put off liability onto someone else while they walk away free. If all principals are held liable, it is likely that a disgruntled or frustrated partner will sell the others out.
If you have tax questions, an experienced attorney can help.