You need to clear customs when entering a new country (BVI to USVI or vice versa.) Clearing customs into the USVI is usually done at Cruz Bay, St. John or Red Hook, St. Thomas. Clearing customs into the BVI can be done at Soper's Hole on the west end of Tortola or Great Harbour, Jost Van Dyke. The process of clearing customs typically takes 45 minutes.
Clients starting their charter in St. Thomas need to clear customs once they enter the BVI; this is also when you pay the BVI Cruising Tax and National Park Permit fees. You can clear out of BVI customs at the same time, you just need to indicate how many days you'll be in the BVI. US citizens can pre-register on ROAM which allows you to check back into the USVI with your phone - otherwise, you need to check into the USVI in person.
Clients starting their charter in Tortola need to clear out of the BVI, into and out of the USVI (can be done at the same time if you indicate how long you’re staying in the USVI) and then back into the BVI.