Moved from Alberta to BC | Income tax filing | Discussion forum

According to the Federal Income Tax and Benefit Guide (2020), one files with the province where one resides on December 31, 2020:

Which income tax package should you use?

Forms and publications
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Use the income tax package for the province or territory where you resided on December 31, 2020. However, there are exceptions, such as if you have residential ties in another place. For more information on these exceptions, see the chart below.

If you resided in Quebec on December 31, 2020, use the income tax package for residents of Quebec to calculate your federal tax only. You must also file a provincial income tax and benefits return for Quebec.
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That's correct: One cannot just use one's new address on the NETFILE'd return.

It looks like doing so would cause issues, according to the NETFILE terms and conditions:

To NETFILE your T1 return, you must agree to the following terms and conditions:
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• If I am not a first time filer, I understand and agree that I cannot change my name on the return. This personal information is not transmitted with my return when I use NETFILE. If I am using the Change my address service in the software, all changes must be made in My Account prior to the transmission of the return. If I have not signed up for email notifications from the CRA, my Notice of Assessment and refund will be sent to the address on file with the Canada Revenue Agency not to the address I entered using the software to prepare my tax return.

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Canada.ca page says you can change CRA address by phone:

Before you call To verify your identity, you'll need

Social Insurance Number
Full name and date of birth
Your complete address
An assessed return, notice of assessment or reassessment, other tax document, or be signed in to My Account
If you are calling the CRA on behalf of someone else, you must be a legal representative.

Telephone number
1-800-959-8281

If things haven't changed, you can also file a paper return in the proper province with the new address. I've done it.
RetirEd