In my mind, the home office rightfully belongs to the shareholder and not the corporation.
The way I would treat this is that the corporation RENTS the home office space from the shareholder. The corporation will claim a RENT expense on their corporate T2 Return, and the shareholder will then claim the rental income on a T776 form on their personal T1 Tax Return. The Rent that the shareholder charges the corporation for using their personal residence for the home office should be reasonably small so that the shareholder can fully right off these costs by their applicable deductions. The net loss incurred on the T776 should then be ZERO'd out, so that the shareholder does not use this loss to reduce other personal income (much like claiming business use of homes on a T2125 form).
ie: Suppose you use 20% of your home for Business Use of Homes by the corporation. Then 20% of all your expenses will be used to offset the Rental income on the T776 (Mortgage interest, insurance, property taxes, utilities). The result should be a Net Loss, which you Zero out, so that you never pay tax on this money, nor do you need to consider carrying forward this loss to future years if you always maintain this net loss scenario. In other words, your intention, as a shareholder, is not to make a profit from the corporate use of this home office.
I hope this is helpful. This is my perspective. I don't have an accounting designation, so you may want to consult an accountant for other solutions.
