As per the Canada Revenue Agency(CRA), you have to file either T777 or T777S form only for claiming the home office expenses. T777 Form is for those working from home due to the COVID-19 pandemic who are only claiming home office expenses, and the T777S form is for those required to work from home or those working from home due to the COVID-19 pandemic who are claiming additional employment expenses like motor vehicle, accounting fees, tools, and parking. For more detail, please refer to the below CRA link: