No penalty is charged if 90% of the correct tax is paid by the original due date of the return.
A penalty of 10% will be added to the tax due if the tax return is not filed by the due date and at least 90% of the correct tax is not paid by that date.
If the return is filed timely but you cannot pay the tax in full, a penalty of 5% will be added to the additional tax due if at least 90% of the correct tax is not paid by the due date.
NOTE: You will never be subject to both the 5% and 10% penalties. The penalty will be the applicable 5% or 10%, but not a total of 15%.
The interest rate may change yearly. Interest must be added to delinquent tax at a per month rate, beginning on the due date of the return and accruing each month until you make full payment of all tax, penalty, and interest due.