I left Canada in Dec in 2021. I served all residential ties after I left. Until then I resided in Montreal Quebec. Can I use turbo tax to file 2021's tax return?

What is the exact message that you are seeing? It may be that you are entering something on your return that is not available in TurboTax Deluxe Online, such as foreign income or self-employment income.

Here are the sequence of pages that I have observed.

1. Chose "Assist and Review Premier"

2. Indicated that I was a non-resident on Dec 31, 2021. I moved out of Canada in the beginning of Dec 2021. Up till then I lived in Quebec.

3. Turbo tax told me that it could not serve me.   Chossing Assist and Review PremierIndicate that I was non resident on Dec 31, 2021Turbo tax told me that it can not serve me

Unfortunately, TurboTaxLive™ Assist & Review services are not available for non-resident returns.

You can still use our regular TurboTax Premier Online, but please note that you will need to pay with a Canadian or US credit card, or use our mobile app to pay through Apple Pay or Google Pay.