What should be the traveler's immediate next step if a trip is canceled after expenses were incurred?

When a trip is canceled after expenses have been incurred, the most appropriate immediate next step for the traveler is to file a claim for reimbursement. This action is essential because it allows the traveler to recover any costs they may have already paid out of pocket or have been charged for services that will no longer be used due to the cancellation. Filing a claim ensures that the financial implications of the canceled trip are addressed promptly, thereby minimizing potential losses and maintaining proper financial records.

The other options, while they could be part of the traveler's overall response to the situation, do not directly address the immediate concern of recovering expenses. Submitting a new trip request would not be relevant until the original issue of reimbursement is resolved. Canceling all future trips may be an overreaction and does not directly relate to the immediate concern. Informing colleagues may be necessary for communication, but it does not address the financial aspect that requires immediate attention.