Make your tax instalment on time to avoid interest charges. March 15 is the 1st instalment due date for the 2012 tax year. You only need to make an instalment if you received a request from CRA. You would receive a request if you owed more than $3000 in either 2010 or 2011. You have to make your instalments to avoid the interest penalties. If your situation has changed and you expect your tax bill to be lower in 2012, you may decide to adjust your instalment but it would be prudent to let us review your situation before making that potentially costly decision. If you did not receive an instalment request from CRA, you do NOT have to make an quarterly tax instalment.

http://www.cra-arc.gc.ca/tx/ndvdls/tpcs/ncm-tx/pymnts/nstlmnts/wh-eng.html