Thank you for your question.
As per the Canada Revenue Agency (CRA) Eligibility criteria – Detailed method, the detailed method of calculating home office expenses is applicable to eligible employees only. You would still be able to claim home expenses related to rental income and home office expenses for self-employed using the flat rate method.
Here is a TurboTax link that you may find helpful - Self-Employment and Rental Income Centre.
Thank you for choosing TurboTax.
