People get IRS problems for the smallest things-neglecting to file taxes on time, not filling out the tax forms appropriately, rounding up the indicated income amounts, you name it. But perhaps the worst "small" thing a person can do that can get him into a lot of snowballing tax problems is to ignore a notice that lands on his doorstep. The IRS is reaching out to you: don't ignore them.
But what do you do when you open that notice and find out there's been an irregularity with your tax returns?