Some £10m a year will be distributed to charitable causes following the death of island businessman Albert Gubay.
Mr Gubay, who died on January 5 at the age of 87, set up The Albert Gubay Charitable Foundation in his later years.
Trustees have now revealed initial plans for where some of his fortune will distributed.
The Derwent Group, an island-based group of property companies now owned by the charity, is estimated to be worth about £700m.
In a statement the trustees said that Derwent Group will reinvest at least half of its annual profits to ensure continued growth but the rest will be distributed to charitable causes, initially at an estimated £10m a year but rising to £20m annually.
Foundation director and trustee John Nugent said: ‘We estimate that the initial donations will be up to £10m each year.
‘This is an arrangement that will exist in perpetuity, continually growing and making ever greater distributions, for generation after generation and because of the way that Albert Gubay positioned The Derwent Group, growth will come very quickly.
‘We estimate that the annual distributions of up to £10m will rise in the next five years to up to at least £20m each year.’
During his lifetime, Mr Gubay made a series of substantial donations to local charities, including £500,000 each to the Manx Sports Aid Foundation to fund scholarships for talented young sportsmen and women and the Department of Education to help young Manx people attend world-leading universities.
He also gave £20,000 sponsorship to help the island stage the 2011 Commonwealth Youth Games.
In 2011 Mr Gubay was given a Papal Knighthood for his service to the Roman Catholic Church.
Rent paid by Derwent Group’s tenants is now effectively being paid to charity and each year it is estimated that up to 40p of every £1 of that rent will end up being spent on worthwhile causes, with the proportion increasing over the next five years.
The Foundation says the charity will be run in accordance with the guiding principles of its founder including that ‘every penny made will be used to help someone and every penny wasted is lost to someone in need’.
It hopes to make its first donations as early as the autumn of 2016, but with the full application and vetting processes unlikely to be in place to deal with those distributions by then, the trustees say they will not accept applications this year and will identify appropriate projects instead.
From 2017 onwards the annual donations will be made via the application procedure.