Scrapping Air Passenger Duty in Northern Ireland completely would cost £3 million, the finance minister has said.
Abolishing the duty would be a price worth paying to preserve the link with North America and attract investment, Sammy Wilson told the Assembly.
Chancellor George Osborne has confirmed his decision to cut the levy and devolve its control to the Stormont Executive.
Mr Wilson said: "To have the transatlantic link with North America was important. It is perhaps only a minor reason as far as attracting tourists, the importance of this was to get the business connections and the return there would be in investment from that easy connectivity with North America."
The move followed warnings that Northern Ireland's failure to match the lower Air Passenger Duty (APD) rate of the Irish Republic could make long-haul flights from Belfast uneconomical.
Continental Airlines had said the existing rate added £60 to every US flight from Belfast International Airport and could force the transatlantic route to be axed.
The cost of the tax has been threatening to kill off the daily service between Belfast and New York.
The flight is operated by Continental Airlines, which also operates a daily service from Dublin. However, the tax out of Dublin Airport is just three euro and Continental said it had been absorbing the cost in Belfast to avoid passengers simply opting for Dublin.
The change will come into force on November 1, when APD will fall to the lower short-haul rate - £12 per passenger in economy and £24 for business and first-class passengers.