To Change your birth date using a TurboTax Online product, please follow the steps below.
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Sign in to your TurboTax and on your current tax return, click the Find button in the top right corner.
Type "Personal Information" - Personal Information - Name and Birth Date will appear, Choose this option and press Go.
The page - Let's get your personal information will appear, on this page you are able to change your Birthdate or any other changes required in your tax return.
Thank you for choosing TurboTax.