Per the CBSA D Memorandum D3-5-2 (attached below):

ACI requires the same voyage number transmitted in applicable fields on all reports associated with tugs, barges, and cargo involved in the following scenarios:

• A tug pulling one or more barges with cargo: Cargo reports must be transmitted for the cargo on each barge, referencing the corresponding Conveyance Reference Number

• A tug pulling one or more barges without cargo: If there is no cargo on any of the barges being pulled by the tug, there is no requirement for ACI cargo reports

• A tug carrying goods that are not on a barge: Cargo reports must be transmitted for the cargo, referencing the conveyance reference number of the tug

• An in ballast (empty) tug that is not pulling barges: Not required for ACI cargo reporting