Do you have electric service?

But for that 30% you need to have a electric hook up usually for them. 

Also, plumbing and electrical lines running it could be a big cost depending on your home layout.

My boyfriend is an electrical contractor with experience in all areas of construction and our plan was to build the duplexes ourselves and I would then manage the rentals for my investors.

I’d just advise you if you’re not otherwise interested in real estate to set aside a small portion of the rent each month for the time period when you will eventually have a vacancy so you have money to pay the mortgage, a small portion for maintenance costs, and a small portion for capital expenses such as when you need a new refrigerator or a new roof every 30 years.

If you have the other expenses, such as the property taxes, water and sewer bills, heating bills if the landlord is responsible for those, electric bills if there is a landlord account, and any other bills you as the landlord would be responsible for monthly you can total them up and see if they will be more or less than the $900/month rent your apartment will generate once you eventually move out of it.

The electricity utility account is under my name (a mistake, I know).

Construction companies as well (HVAC, electrical, plumbing).

For starters, what about your other expenses like landscaping/lawn and tree care, snow removal, vacancy loss, water, sewer, trash, gas, electric?

I use decorator receptacles and rocker switches, and new wall plates, to improve the look of the electrical and make it all match.