According to IRS, the fines for failure to file by the deadline are as follows:
    Two penalties may apply. One penalty is for filing late and one is for paying late. They can add up fast. Interest accrues on top of penalties
    
    Penalty for late filing. If taxpayers file their 2016 tax return more than 60 days after the due date or extended due date, the minimum penalty is $205 or, if they owe less than $205, 100 percent of the unpaid tax. Otherwise, the penalty can be as much as 5 percent of their unpaid taxes each month up to a maximum of 25 percent. 
    
    Penalty for late payment. The penalty is generally 0.5 percent of taxpayers’ unpaid taxes per month. It can build up to as much as 25 percent of their unpaid taxes.
    
    Combined penalty per month. If both the late filing and late payment penalties apply, the maximum amount charged for the two penalties is 5 percent per month.