T3 joint account - Each owner of a joint account is required to report their individual portion of the total income according to the same ratio as their proportionate contribution of funds to the joint account.
Although a single T3 tax slip may be issued for your joint account in your name with your SIN#, doesn’t mean that the CRA is expecting you to report all the income. They only want one SIN to be included on the tax slip. Therefore, only the primary account holder’s SIN number is displayed on it.
How do I enter a T3 slip? -https://turbotax.community.intuit.ca/replies/2647675