If you are claiming the employment expense deductions, you would have to answer YES to the question "Were you required to pay for expenses related to your home workspace that weren't fully reimbursed by your employer?" In order to qualify for this tax deduction. Then click on Continue, where you will be given an option to choose between the flat or detailed methods of employment expense. 

Note: For the flat rate method to be activated in TurboTax Online, you enter your T4 and scroll down to the bottom where you will be asked: Will you claim employment expenses for working at home due to COVID-19 for income on this T4? NEW! Please say YES to this question. 

For more information please follow this link:

• How to claim your Covid-related employment expenses in TurboTax 

Thank you for using TurboTax.

Thanks for the reply. flat-rate option applied 🙂 

I have purchased Turbo Tax Standard version, and I cannot apply the Option 1 with the flat rate. there is no question at the bottom of my T4 to activate this. What should I do? 

@Mihai Neagoe Are you using TurboTax CD/Download in forms mode? If so, please scroll up to the top of the form. You need to have all the eligibility checkboxes ticked, and then tick off Option 1 for the form to calculate properly.