You are eligible to use the flat rate 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 pandemic. If you were not required to work at home but your employer gave you the option to work at home because of COVID-19, you can still qualify. You can use the flat rate method only if you do not claim other employment expenses. In other words, you can use the method if you claim only home office expenses.
Under the flat rate method, you can deduct $2 for each day that you worked from home in 2020 because of COVID-19. The maximum you can deduct under this method is $400 (that is, $2 x 200 days). As a result, you should use this method only if you are not eligible for more than $400 of deductions under the regular rules.
The CRA has indicated that the flat method can be used for the 2020 tax year. It has not indicated whether the method can be used for the 2021 year.