The announcement suggests that mariners postpone paying for their examinations until ready to take the exam to avoid the lengthy wait for mariners who did not test and are entitled to a refund.
Update to Pay.govPatricia2018-09-18T11:52:32+00:00
February 6, 2016: The site for paying credential fees, Pay.gov, has been significantly updated. Mariners will now be able to pay for multiple transactions, for example officer and ratings endorsements, on a single page. To get to the NMC site, go to “Find an Agency” and click under “H,” for “Homeland Security: US Coast Guard, National Maritime Center.”