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

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!