You can claim input tax credits (ITCs) and input tax refunds (ITRs) for home office expenses only if the work space in your home:

• is your principal place of business; or
• is used exclusively (90% or more) to earn income from your business and to meet persons on a regular and continuous basis in the course of your commercial activities.

The same criteria are used to calculate an individual's deductible home office expenses for income tax purposes.