Self-employment Losses
Self-employment losses can be carried back 3 years, and can be used to offset other income.
If you are self employed and had a loss for tax purposes in your latest tax year, but had no other income against which to offset this loss, you can carry back this non-capital loss to any of the prior 3 taxation years. To do this, you have to file a form T1A, "request for loss carry back". See the article on changing your tax return.