You lose a small amount, but there's not much fluid higher than the filter to lose. All in the sump. Be gentle with the hard lines--that little filter likes to stay put.
The trick on Kubota's when changing the filter but not the fluid is a shop vac. Get a helper of tape the hose to the fill hole & turn it on. The vacuum in the tank will prevent fluid from escaping. I'm sure it works for other makes as well.