If it helps at all this isn't specific to this cab company. I'm in exactly the same boat as you - pay the Chicago cabby with the Amex and then take care of it in my employer's expense reporting tool. The way it works is the tool pulls everything down from Amex everynight and then you go and categorize your charges and submit them. So you'll go take care of everything - hotel, flight, etc right after the trip, and then like 0 - 5 weeks later quasi-random taxicab charges start showing up. I'm assuming it's tied to when the driver needs money or something.