If you have an outstanding tax liability owed to the California Franchise Tax Board (FTB) past the due date, your tax bill is at risk of growing much larger over time. By law, the Franchise Tax Board must charge interest on unpaid taxes. This interest is charged from the due date until the date it is paid, is adjusted twice a year, and compounds daily.
On top of this interest, a delinquent penalty rate is charged. The rate is 5% of the total unpaid tax, and a further 0.5% for each month or part of a month over the due date that the tax remains unpaid, up to 40 months. Other penalties for returned checks, understatement, negligence and fraud may also add to the overall total owed to the FTB. There is no “reasonable cause” exception for interest due on your tax assessment. In some specific cases, however, you may qualify for tax interest penalty abatement. This concession from the FTB can make paying your late taxes less of a burden.