Interest is due on delinquent business tax and is also payable on business tax refunds. Additional interest accrues with each month in delinquency. The interest rate is re-calculated annually to reflect the average Federal short-term rate plus 3 percentage points.
| Tax Year | Monthly Interest Rate |
|---|
| 2025 | 0.7% |
| 2024 | 0.7% |
| 2023 | 0.5% |
| 2022 | 0.3% |
| 2021 | 0.5% |
| 2020 | 0.5% |
| 2019 | 0.5% |
| 2018 | 0.4% |
| 2017 | 0.3% |
| 2016 | 0.3% |
| 2015 | 0.3% |
| 2014 | 0.3% |
| 2013 | 0.3% |
| 2012 | 0.3% |
| 2011 | 0.3% |
| 2010 | 0.4% |
| 2009 | 0.5% |
| 2008 | 0.7% |
| 2007 | 0.7% |
| 2006 | 0.6% |
| 2005 | 0.5% |
| 2004 | 0.4% |
| 2003 | 0.5% |
| 2002 | 0.6% |
For 2001 and prior years, interest accrued at a rate of 1.25% per month.