this was on the front page of the company website today
American Express has changed how they process late fees for Corporate (Travel) Cards.
Starting with the billing period beginning January 1, 2019, American Express will charge a late fee if your payment is not received on the Next Closing Date of the billing period. Previously, you had to make the required payment within 15 days after the Next Closing Date to avoid the late fee.
The late fee remains unchanged at $39.00. Please make sure to submit your expense reports timely to avoid any late fee charges to your American Express Corporate Card account.
To assist in getting payments to American Express on time, we will begin processing payment for expense reports twice a week, on Monday and Thursday.
it's unclear whether corporate travel accounting will reimburse late fees, but I suspect not -- even though I can't file an expense report before completing the trip