There are many civil penalties available to the IRS. These are the most commonly applied:
Failure-to-File (I.R.C. § 6651(a)(1)). generally 5% of the amount of tax required to be shown on the return per month, up to a maximum of 25%.
Fraudulent Failure to File (I.R.C. § 6651(f)). generally 15% of the amount of tax required to be shown on the return per month, up to a maximum of 75%.
Failure-to-Pay on time (I.R.C. § 6651(a)(2)). Generally, 0.5% of the amount of tax shown on the return per month, up to a maximum of 25%.
Failure to Pay Estimated Taxes (I.R.C. § 6654). Generally, this amount is 3% above the federal short-term lending rate .
Accuracy-Related Penalty (I.R.C. § 6662). Generally, 20% of the underpayment.
Fraud Penalty (I.R.C. § 6663). Seventy-five percent (75%) of the part of the underpayment attributable to fraud.