You may have made an RRSP contribution in the previous year, but didn’t record this on your return. For instance, if you made RRSP contributions from March 1, 2010 to March 1, 2011, this should have been included on Schedule 7 which was filed with your 2010 tax return. If you omitted any of the RRSP contributions during that period from Schedule 7, you will have to file an adjustment to your 2010 tax return. You should be able to file a T1Adj online without submitting receipts, and if Canada Revenue Agency wants to see copies of the receipts they will request them from you. See our article on changing your return.
You then have 2 options regarding your 2011 tax return:
1. Wait for the reassessment notice for your 2010 tax year before filing your 2011 tax return (as long as you can still file for 2011 by April 30th), including the 2010 contribution as a carry-forward from 2010, or
2. File your 2011 tax return without the carry-forward from 2010, and subsequently file a form T1Adj (as above, can be done online) requesting a change to your 2011 tax return to include the carried-forward contribution from 2010, and to claim the RRSP deduction.
In order to avoid problems, it is best to include all RRSP contributions made in the first 60 days of the current year on Schedule 7 of the tax return for the past tax year.