Do I have to have my spouse on my return or can we file separately. But mention we are common law

You can file your tax return separately, and indicate you are common-law on each of your returns.  

For further information, please see the link below:

TurboTax Article: Facts Every Canadian Needs to Know About Filing Coupled Tax Returns.

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Yes, you can file your returns separately and indicate that you are common-law. 

In online versions of TurboTax, you can prepare your spouse or common law partner's tax return at the same time as yours. This is called a spousal/coupled return. If you’ve already started your return but haven’t indicated that you want to prepare together, you'll need to start a new return and indicate that you want to prepare your spouse or common-law partner’s return together with yours.

TurboTax FAQ on how to file a coupled return: How do I prepare a spousal or coupled return in TurboTax Online? 

Thank you for choosing TurboTax.