If you have a balance owing for 2010, the Canada Revenue Agency charges compound daily interest starting May 1, 2011, on any unpaid amounts owing for 2010. This includes any balance owing if your tax return is reassessed. In addition, you will be charged interest on the penalties starting the day after your return is due. The rate of interest charged can change every three months. See prescribed interest rates.
If you have amounts owing from previous years, the CRA will continue to charge compound daily interest on those amounts. Payments you make are first applied to amounts owing from previous years.
If you owe tax for 2010 and do not file your return for 2010 on time, the Canada Revenue Agency will charge you a late-filing penalty. The penalty is 5% of your 2010 balance owing, plus 1% of your balance owing for each full month that your return is late, to a maximum of 12 months.
If you were charged a late-filing penalty on your return for 2007, 2008, or 2009 your late-filing penalty for 2010 may be 10% of your 2010 balance owing, plus 2% of your 2010 balance owing for each full month that your return is late, to a maximum of 20 months.