No, the Canada Revenue Agency (CRA) will not automatically add your dependents if you forgot to put them on your taxes. If you have already e-filed your taxes and realize you have forgotten to include your child-dependent information, you must submit an adjustment to your tax return after you receive your Notice of Assessment (NOA), as suggested by the CRA.
To make a change to your tax return, you can use the CRA's "Change My Return" service through your CRA My Account, or you can complete and submit a Form T1-ADJ, "T1 Adjustment Request". You will need to provide the correct information about your dependents on the adjustment request, and the CRA will review and process your request.
For more information please see this Canada Revenue Agency website: ReFILE: Online adjustments for income tax and benefit returns
For more information, please see our TurboTax FAQ. How to Change Your Tax Return AFTER You’ve Filed
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