Where do I enter a non-capital loss?

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If you are using TurboTax Desktop you will enter your non-capital loss on line 25300. 

How do I deduct losses?

Your current year notice has your net capital losses from previous years and any unused capital losses from the current tax year. Add these two amounts together to determine your available net capital loss for the future tax year; use this to offset any capital gains you may have in the current year.

Claiming a Net Capital Loss

Understanding Business Investment Losses