US Canada cross border tax issues

[ek888199]

I am a Canadian who lives in Toronto. 

Company A and B contract me as a safety inspector. Company A – Canadian company registered in Toronto; Company B – American company registered in Houston, TX. As a safety inspector I visit customers of company A or company B. Customers can be located in either US or Canada. As a result I have 4 situations:

1. Company A (Canadian) contracts me to visit their customer in Canada
2. Company A (Canadian) contracts me to visit their customer in US
3. Company B (American) contracts me to visit their customer in Canada
4. Company B (American) contracts me to visit their customer in US

Considering these 4 situations, what scenario makes me liable for paying GST?

[TurboTaxSusan]

If you are doing business in Canada with a Canadian company, then yes you would need to charge GST if you are registered.

If you are in the US doing business with a US company, then you probably don't have to charge GST.

The other two scenarios are no so clear cut, and it would be a good idea to contact the CRA and double check with them.