The penalty for the late filing of federal tax form 4972, which is used to report the tax on lump-sum distributions from qualified retirement plans, is usually 5% of the unpaid tax amount for each month or part of a month the return is late, up to a maximum of 25% of the unpaid tax. However, if there is a reasonable cause for the delay in filing, the IRS may waive or reduce the penalty. It is always advisable to consult with a tax professional for specific information related to your situation.