US Citizens Working in Canada

[justatester]

I have a plan that have several US citizens who work and live in Canada. They are employed by a US company and are participants in the US DC plan. They are paid in Canadian dollars.

Question: I assume they need to be tested in the US plan since they are participating. Do I convert their Canadian salary to US dollars?

Also, are there any special Canadian rules that need to be followed? Similar to PR participants.