[Vaquero]

Aren’t they all part of a commonwealth already?

[sinsofsolarempirefan]

Yes, but until the late 1940s, these nations had defacto shared citizenship and could move freely, then citizenship laws began to be introduced that created seperate citizenships instead of shared ‘British Subject’ status. CANZUK would make freedom of movement within the Dominion States (those which share the Crown) a thing again.

[Cronos]

the commonwealth is a talking heads shop. No real trade zone

[Sam Gamgee]

The commonwealth really doesn’t mean anything anymore these days. The nations in question do have a Commonwealth Games every so often. But that is about it. We share much culturally and politically of course, but there is not formalized commonwealth anymore.

[Rapace376]

Vaquero, yes they are. Except this is entirely different. I would recommend reading Will CANZUK bring back the British Empire after Brexit?, it's a little more optimistic than what most of the comments say!