The UN Tax Committee on International Cooperation on Tax Matters has 25 individual members who are appointed by the UN Secretary General and who meet twice a year to work on the UN tax agenda.
All the other 180 UN member countries can participate in these meetings.
The UN Tax Committee has been re-established over the past 10 years or so as a Committee of Experts. The individual members of the Tax Committee are appointed every four years, for the next four year period.
The members of the UN Committee of experts have just been announced, in August 2017l and will serve until 2021.
There are 6 members from each of Africa and the Far East, 5 from Europe , 4 from South America and one each from the Caribbean, Canada and New Zealand.
The full list of the UN Committee of Tax Experts can be accessed here.
There is no representative from the United Kingdom or the United States.
The League of Nations worked to produce a model Double Tax Treaty in the period between the First and Second World Wars.
This work has been carried forward by the UN and there is now the UN Model Double Tax Convention.
The current updated version of the Double Tax Convention was published on 11 July 2017 for comment on the new parts and with a view to being published in the near future.
In the aftermath of the Second World War OECD stepped into the void left by the League of Nations and worked on its own Model Double Tax Convention as well as, more recently, working on Transfer Pricing Guidelines, of which the first version was published in 1995.
In very recent times the OECD has worked on the Base Erosion Profit Shifting Action Plan with a view to updating the international tax regime so that international business is taxed by reference to the place where it carries on that business and makes its profit.
Currently there is more cooperation between the international organisations, most recently through the Platform for Collaboration on Tax which in addition to the UN and OECD involves IMF and the World Bank.