* https://www.canada.ca/en/revenue-agency/services/e-services/...
* https://www.canada.ca/en/revenue-agency/services/e-services/...
* https://verified.me/government-sign-in-by-verified-me/
You can also create a stand-alone account with the CRA if you wish. Other federal agencies use the 'partner' system as well.
It's basically SAML.