The Tonga Trust Fund was established by the Tonga Trust Fund Act on 3 November 1988.

Its purpose was as a kind of safety net for Tonga to accumulate moneys to be held in trust as a foreign reserve fund for the Kingdom to use in exceptional circumstances, and for future major development projects.

Its main sources of funds so far have been from the sale of Tonga Protected Person Passports, Tonga National Passports, from the government’s TongaSat income and from interest earned on investments.  

The 1996 auditor’s report of the Tonga Trust Fund, Gazetted in February 1998, showed that by 31 March 1996 there was $37,074,648 in the Trust Fund, which was invested in the USA and in local banks.

Money from the Trust Fund has been used to finance a number of the government’s development projects. These include tourism marketing, a contribution to the construction of the Queen Salote Memorial Hall, the construction of the new court house in Vava’u, the repayment of government’s international loans, the purchase of a new office building for the Tongan High Commission in London, and other projects.

Under the Trust Fund Act the fund is to be administered by three trustees—the Prime Minister, the Minister of Finance and one other person to be appointed by His Majesty in Council. The appointee is currently the Attorney General Hon  Tevita Tupou.

The Act allows the expenses of administering the fund to  be drawn from the government’s recurrent estimates.