Taxes, fees and port expenses are the charges a cruise line adds to your booking for costs imposed by governments, ports and other third parties. Royal Caribbean's booking conditions list examples such as immigration fees, passenger head taxes, dockage and wharfage fees, pilotage, canal tolls and environmental fees.
They are not part of the cruise fare. Royal Caribbean says they are additional where not included in the price displayed, estimated at the time of booking and subject to change. That last point is why they move for reasons that have nothing to do with how a sailing is selling: a port changes its charges, or an itinerary changes.
For price drops, the number that matters is the cruise fare. CruiseSignal measures a drop on the cruise fare for your cabin category and fare type, with taxes, fees and port expenses listed separately, so a change in port charges is never reported as a price drop. How a line presents these charges in its advertised prices varies, and so does whether its claim rules compare fares with or without them, so check your line's terms before you work out a difference.
On your booking confirmation or invoice these charges normally appear on their own line below the cruise fare. See booked fare for the figure a drop is measured against, and price protection for what each line lets you claim.
