They began working on the business in December last year, and together have invested just under $1 million to get the company off the ground.
Frances Wyborn, ex-wife of Auckland property investor Mark Wyborn, holds a 25 per cent stake in the company.
Mason and Reiri worked under English during his time as Prime Minister and Minister of Finance for the National Party, at the Social Investment Agency.
"We truly believe that we can use data and technology tools and evidence of what works to make a difference in people's lives to serve New Zealand better," Mason told the Herald.
"Like [philanthropists] invest their money into the rest of their lives and know what return they can expect, we wanted to do a much better job of helping them make investment with their philanthropic dollar."
Impact Lab is focused on rolling its analytics tools out to social service providers in New Zealand, before it looks to take the business offshore into Australia, United States and the Pacific Islands.
Mason said the tools could be used in foreign aid, philanthropic spending, corporate social good and responsibility, ethical investing and Government spending.