When the IRS prosecutes, tax evasion is not always the only charge (if it's charged at all). In fact, there are cases where the person who has been found guilty of one crime may also be charged with violating other laws.
Let's say you're married and you file a "married filing jointly" return, since you want to take advantage of the unique tax benefits (lower taxes than other filing statuses, higher standard deductions, and other tax benefits that don't apply to other statuses) offered by this particular filing status.
As of April 30, 2011 The IRS had identified 775,723 tax returns with $4.6 billion claimed in fraudulent refunds and prevented the issuance of $4.4 billion of those fraudulent tax refunds. That is a prevention rate of nearly 96%. This represents a 171% increase in the number of fraudulent tax returns identified during the same period in 2010.