Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

How to determine how much to charge your business for rent (in your house)?
In Canada I think you'd do it as a % of square footage. For example: Then you can count 20% of the cost of the of renting the apartment as a business expense. I expect that conventions (i.e. that what's accepted rather than challenged by the tax authorities) may vary from country to country.