This is a free Productive addon. You have to turn it on to be able to use it.
Go to Settings > Addons and turn on Cost overhead.
What is cost overhead?
It is the amount of money added on top of your employee cost rates (salaries). When people track time, we will deduct both their cost rate and the overhead amount (per hour) from the billable rate, thus increasing the accuracy of the profitability report even further.
Productive calculates overheads based on your average facility costs (office space, software, travel expenses etc..) and on the amount of time you spend on internal projects (like Sales, Finance, HR etc..)
To set up your facility cost go back to Settings and click on Cost overhead.
Click on the Edit cost link, put down the amount you spend monthly on facility costs and Productive will calculate the rest.