The federal government is giving $6 million that will allow tourists from the mainland to take their vehicle on the Spirit of Tasmania at zero cost from March 1 to June 30.

"COVID-19 has significantly affected tourism in Tasmania and the number of passenger vehicles travelling across Bass Strait," Deputy Prime Minister Michael McCormack said in a statement on Thursday.

"Australians can take their car or motorbike to the Apple Isle at zero cost and discover everything this beautiful state has to offer - a win-win for both Tasmanians and visitors looking to discover more of what the island has to offer."

Spirit of Tasmania bookings have dropped 85 per cent during the COVID-19 pandemic.

Assistant Minister for Industry Development and Liberal Tasmanian senator Jonno Duniam said the $6 million boost will bring more travellers to the island, providing the kick-start to 2021 that the state needs to rebuild tourism.

"It represents an average saving of around $240 return for travellers," he said in the joint statement.

"That's money they can now spend at small businesses, with tourism operators and in the many communities that are eager to welcome travellers back with open arms."

Australian Associated Press