The Victorian Government is planning to introduce a US$80 million annual licence fee on the Port of Melbourne, which will pass on the extra cost to importers and exporters.
It is the only container port available to Tasmanian businesses.
The State Government claims the new tax will cost Tasmanian companies $10.75 million a year.
Rob McGuire from the Freight Logistics Council says it would add another $21.5 per container to the cost of shipping.
"It is just another impost on exporters that have already been hit with the loss of the international shipping service ex Bell Bay."
"We have certainly been taken by surprise, there was no consultation with the Victorian Government," he said.
The Tasmanian Government is considering legal action if the tax breaches the constitutional right to free trade between states.
A spokesman for the Victorian Government says the fee is legal and is a fair way to distribute costs across all port users.