December 31, 2010 Deadline for realizing capital losses for application against 2010 or 3 prior years capital gains.
February 28, 2011 T4 / T5 Filing Deadline
Final day to file T4 and T5 returns for 2010 payments.
March 1, 2011 RRSP Contribution Deadline
Final day to make RRSP contribution that can be deducted in 2010 income tax return.
March 15, 2011 First personal income tax instalment for 2011.
March 31, 2011 Deadline for filing 2010 family trust returns (T3) and partnership returns (T5103).
April 30, 2011 2010 Personal income tax return must be filed for all non self employed persons and their spouses.

Personal income tax balances owing for 2010 (including amounts owed by self employed persons) must be remitted prior to midnight to avoid late payment interest.
June 15, 2011 2010 Personal Income Tax Returns for Self Employed persons and their spouses must be filed.

Second personal income tax instalment for 2011.