In each of the following Cases, determine whether the employment income is taxable in Canada:

Case 1 David resides in the state of Washington. He accepted temporary employment as a technician with a Canadian company to do service calls in the Vancouver area for four months beginning September 1, 2020. The Canadian employer agreed to pay him $2,800 Canadian per month. David remained a non-resident of Canada throughout his Canadian employment. Case 2 Assume the same facts as in Case 1, except the employer was resident in Washington and did not have a permanent establishment in Canada. Case 3 Sandra resides in Detroit, Michigan, and has commuted daily to a full time job in Windsor, Ontario, for the last three years. In 2020, she spent 238 days at her job in Canada. She works for the municipality of Windsor and earned C$50,000 in employment income. Sandra is a U.S. resident throughout the year.