How much total rent/utilities to input for home office employment expenses when sharing home

[prankmunky13]

My spouse and I have worked from home since the very start of the pandemic (March 16). We rent a house and pay a considerable amount of rent ($3500/month) so it may be better for us to use the detailed method to deduct home office expenses than the COVID flat rate method. We both have requested and received the T2200S forms. 

After determining the percentage of space/time used for work at home using the online CRA calculator (i.e. % of your home used as a work space and for employment purposes). Do we each apply this percentage to the full amount of rent and utilities in that time period or just half that amount each since we conceptually split rent and utilities payments between us. I assume its half the amount but this isn't really clear anywhere and we don't want to miss out any deductions that we are eligible for. 

Example: My home works space is in 150sqf of a common room in 1500sqf house (10%). If I worked 38h a week in the common space that's 22.02% hours of work a week in that space. So 2.26% of my home was used for employment purposes. I would then apply 2.26% to half of the rent and utilities ($18000) rather than the full amount that we incurred during that period ($36000) and thus input $406.80 into the "Amounts included above that relate solely to the work space in your home" box in the TurboTax Employment Expenses - Enter the expenses for the period during which you worked from home section.

Is that correct? Thanks in advance!

[prankmunky13 · Accepted solution]

Consensus from other finance forums is to actually use the whole amount of rent and utilities for the house. 

Basically if you use 10% of a house for work, then 10% of the full rent and utilities were consumed by that workspace. If you lived alone your rent might be half but then the percentage of space used would go up so it would still average out to a similar deduction.

Also figured out on my own that you don't input this value into the "Amounts included above that relate solely to the work space in your home". The calculation happens on its own behind the scenes. That box is only if items that were truly only paid for that space and not shared across the house. 

[hanseouloh]

The part that I'm confused about is that the CRA website itself says that if you use a designated room for the office, the cost is not affected by the number of hours you use the space for work... why does TurboTax automatically assume all expenses are in a common/shared space?

[prankmunky13]

It doesn't (in the premier downloadable version anyway).

In the "What type of work space do you have at home?" section, you need to select the check box next to "Designated Space (Example: a room)" rather then the one next to "Common Space (Example: a dining table)".

Just remember the CRA has been clear that even if your workspace is an entire room but is also used for anything but work at any other time (for example the computer is shared with the family after hours, or it doubles as a guest room), than it actually needs to be treated as common space for tax purposes. 

[hanseouloh]

this option doesn't seem to be available for me on the online version.