We can certainly guide you to change your SIN number on TurboTax. Please find below the steps to be followed:

1. Sign in to your TurboTax account, and make sure you click continue under your tax return.
2. Go to the top right of your return and click on "My info"
3. The system will show you a list. Please click on personal information.
4. Your Social Insurance Number will be presented in the fourth box. If you are able to and the old number is not "greyed out" you can change this to your correct SIN number. If you are unable to change it here, you have no option but to start a new return with the correct number.
5. Once you finish this process scroll down, and press “Continue” to save the changes.

If you have Netfiled your return you are not allowed to change your SIN. If you filed a tax return with an incorrect SIN, you will need to contact CRA directly to explain the situation and see if they can rectify this for you

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