I read the United is working on getting the imputed income numbers back into the system. Hopefully soon so we have some type of idea of what our enrolled friends would have to pay.

Friendenrolled, it was probably 0.00 to fly to LHR because the cost is coming back from LHR, You might try LHR to IAD and I bet you get a charge. I believe the new system charges you towards the end of listing. I flew United to Belgium a couple of weeks ago and it was no cost, but returning (exit taxes) there was a charge. Enrolled friend would pay the taxes up front but your employee friend would get charged the imputed income (on domestic or international flights) in their paycheck.
Tony