If you fail to file Form 1120-POL on time, the IRS charges an additional fine equal to 5% of the tax due for each month the return is late. This amount cannot exceed 25% of the total amount of tax due. If your Form 1120-POL is filed more than 60 days late, you're required to pay $135 or the remaining tax due, whichever is smaller.
If you receive a notice for a penalty after you make a filing late, reply to the notice with an explanation and the IRS might determine whether you meet the reasonable cause criteria or not. An explanation must not be attached to the return.