Late filing penalty

The penalty under § 685(a)(1) for late filing is 5% (0.05) of the unpaid tax for each month (or part of a month) the return is late. This penalty cannot exceed 25% (0.25) of the tax paid late unless the return is more than 60 days late, in which case the penalty will not be less than the lesser of $100 or 100% of the amount required to be shown as tax on the return.