As an employee, you may be able to claim certain home office expenses (work-space-in-the-home expenses, office supplies, and certain phone expenses).
This deduction is claimed on your personal income tax return. Deductions reduce the amount of income you pay tax on, so they reduce your overall income tax liability.
The new temporary flat rate method simplifies your claim for home office expenses. You are eligible to use this new method if you worked more than 50% of the time from home for a period of at least four consecutive weeks in 2020 due to the COVID-19 pandemic. You can claim $2 for each day you worked from home during that period plus any additional days you worked at home in 2020 due to the COVID-19 pandemic. The maximum you can claim using the new temporary flat rate method is $400 (200 working days) per individual.
Please consult your tax professional or read more on the CRA website