Are you an employee or are you self-employed? Are you using TurboTax CD/Download or TurboTax Online?

I am an employee who has a t2200 form. I am using TurboTax online and I am trying to understand where I need to put the information of my expenses. There are 2 sections where you can add the expenses of the house and the expenses of the section I use as an office. 

I added the information in both sections but it looks like the amount due is getting reduce twice. So I assume that I am doing something wrong,

You only have to enter your expenses in one spot.

"Expenses which you incurred for the entire home" is where you would put things like rent, property tax, utilities, etc... that you can only claim a portion of based on how much of your home you use for work. 

"Expenses which you incurred for office space only (not for entire home)" is for expenses that you just use for work, so you can claim the full amount. For example, if you have an internet connection just for work, then you can enter it here.

What if I only worked part of that year? Do i put in the electricity expenses for the full year anyway? Does turbo tax factor in the start and end dates? Or do i just put in the amount of electricity used for the entire home during the times that I was employed? I’d imagine this would make a huge difference in the calculation. 

@bracus TurboTax doesn't also for employment start/end dates, so you would have to adjust your amounts to reflect that you didn't work the whole year.