If you are using TurboTax Full Service- then yes, if given permission they will be allowed to retrieve your slips from the CRA. If you are doing your own return then you will need to sign into your CRA My Account in order to retrieve your T4A slips.
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I will be getting my T4 slips in the mail, but my wife's cannot be sent to me. She is in long term care, we have had to change addresses last year, and, obviously, having to live apart. If you can get my wife's T4 slips I will gladly pay for you to prepare our tax returns and nettle them!
If your wife is able to give verbal permission than TurboTax full service can complete your returns for you. If this isn't possible then you would need to get authorization through CRA.
Thank you for choosing TurboTax.