Canada Life International has unveiled plans for new, purpose-built offices on the outskirts of Douglas.
The move to a new corporate HQ will end the company's long association with Castletown, where its 140 staff are currently spread between two sites, Mill Court and Canada Life House.
The firm's new premises at Ballacottier Business Park are currently under construction by developers Dandara Commercial.
Canada Life set up a sister offshore company in Dublin in 2013 which has outsourced much of its administration work back to the Isle of Man.
The company says that is part of an 'exciting growth strategy' which could see the headcount on-Island rise to 200, making the move to new premises essential.
CLI's Managing Director Sean Christian said:
"Our preference was always to remain in the south of the Island as Castletown has served us extremely well since opening to business in 1987 and I would like to think we have become an important part of the local community."
"Sadly, after considering the limited number of potential options over the last five years we concluded that there were no viable new developments or existing premises to accommodate our future needs in the south of the Island."
"The new development at the Ballacottier Business Park provides us with the flexibility to design a bespoke headquarters to cater fully for our future needs as well as providing ample car parking facilities which are not always possible with town centre developments.”