It hardly ever raises to the level of crime. The issue is that the IRS has 7 years to audit a tax return, and since taxes are due at the time you receive the i

It hardly ever raises to the level of crime. The issue is that the IRS has 7 years to audit a tax return, and since taxes are due at the time you receive the income, the interest is backdated if you happen to underpay taxes and it compounds. So if they audited your 2019 return today and you underpaid $1k, you’d owe $1333 today with compound interest over those 6 years.