You are correct, that when your business does not sell products or inventory, you do not have COGS.
However, you do have COS (Cost of Sales) which are cost you can attribute to a particular job you do.
For example, specific material purchased for particular job such as lumber or tile for just the one job.
COGS/COS (Direct cost) are all same line on income statement where those cost are subtracted from revenue to get GROSS Profit before subtracting (Indirect) cost to get to the bottom line of NET Profit.
Unfortunately, QB has kept the line COGS for the last 30 years, so you must use COGS for COS also. Perhaps this has been updated since I last looked, so if you see and option for COS, then use that.
