What does it cost to have a battery replaced in a late 2016 macbook pro 15"?

Yesterday the lid on my late 2016 15" macbook pro would not close all the way. I notice a swelling of the case where top and bottom have separated. I run plugged in most of the time and have never seen a problem indicator on the battery. Now the battery status says "Service Recommended".

I have not contacted Apple service yet. Does anyone know what the cost is to replace the battery?