What are previous and current interest and estimate penalty rates?

Current interest rates

The current rate (valid from July 1, 2009 to December 31, 2009) on personal income tax underpayments and overpayments, corporation underpayments, and estimate penalties is 5%.
The current rate on corporation overpayments is 0%.

From	To	Interest rate¹	Corporation overpayment rate
January 1, 2009	June 30, 2009	5%	2%
July 1, 2008	December 31, 2008	7%	3%
January 1, 2007	June 30, 2008	8%	5%
July 1, 2006	December 31, 2006	7%	4%
January 1, 2006	June 30, 2006	6%	3%
July 1, 2005	December 31, 2005	5%	2%
July 1, 2004	June 30, 2005	4%	1%
July 1, 2003	June 30, 2004	5%	1%
July 1, 2002	June 30, 2003	6%	2%
January 1, 2002	June 30, 2002	7%	1%
January 1, 2001	December 31, 2001	9%	1%
January 1, 2000	December 31, 2000	8%	1%
July 1, 1999	December 31, 1999	7%	2%
January 1, 1999	June 30, 1999	8%	2%
July 1, 1995	December 31, 1998	9%
January 1, 1995	June 30, 1995	8%
July 1, 1993	December 31, 1994	7%
January 1, 1993	June 30, 1993	8%
July 1, 1992	December 31, 1992	9%
July 1, 1991	June 30, 1992	10%
January 1, 1990	June 30, 1991	11%
July 1, 1989	December 31, 1989	12%
October 1, 1988	June 30, 1989	11%
April 1, 1988	September 30, 1988	10%
January 1, 1988	March 31, 1988	11%
October 1, 1987	December 31, 1987	10%
January 1, 1987	September 30, 1987	8%
July 1, 1986	December 31, 1986	9%
January 1, 1986	June 30, 1986	10%
July 1, 1985	December 31, 1985	11%
January 1, 1985	June 30, 1985	13%
July 1, 1983	December 31, 1984	11%
March 1, 1983	June 30, 1983	16%
January 1, 1983	February 28, 1983	14%
May 27, 1982	December 31, 1982	18%
January 1, 1976	May 26, 1982	12%
Before January 1, 1976		6%

¹Personal income tax underpayment and overpayment, corporation underpayment, and estimate penalty rate.