Penalties play an integral role in tax administration by:
| - | deterring non-compliance by making it unprofitable to taxpayers; | |
| - | promoting equity among taxpayers by ensuring that those who meet their obligations are not disadvantaged in comparison with those who do not; and | |
| - | compensating the Government for being denied the use of funds that it is entitled to. |
Territory Revenue Office’s penalty policies are contained in Commissioner's Guideline CG-GEN-002 for taxes and stamp duty and Commissioner's Guideline CG-HI-002 for the first home owner grant.
Interest rates for the current and previous four financial years, are detailed below:
| Financial Year | Premium Rate | Market Rate | Total |
| July 2008 to June 2009 | 8% | 7.75% | 15.75% |
| July 2007 to June 2008 | 7% | 6.37% | 13.37% |
| July 2006 to June 2007 | 7% | 5.87% | 12.87% |
| July 2005 to June 2006 | 7% | 5.68% | 12.68% |
| July 2004 to June 2005 | 7% | 5.51% | 12.51% |
| July 2003 to June 2004 | 7% | 4.77% | 11.77% |
| July 2002 to June 2003 | 7% | 4.84% | 11.84% |