It enables information sharing about details of accounts at many institutions, including banks, private equity funds, investment advisers and some brokers and trusts.
New Zealand already shares tax information with the likes of the UK, Canada, France, Germany, Japan, South Africa, Israel and Saudi Arabia.
Nash said the expanding list further increases the ability to ensure all New Zealanders pay their fair share of tax, including those who have financial interests in other countries.
Inland Revenue will review the information and verify that the correct tax is being paid on offshore investments.
"New Zealand taxpayers are strongly advised to check they have correctly accounted for their offshore investments. If not, they should make a voluntary disclosure to Inland Revenue without delay," Nash said.
Greens' Co-Leader James Shaw supported the move.
"Tax evaders have been able to avoid paying their fair share of tax that goes towards hospitals and schools, while the rest of us chip in."
He said the Government's move would ensure this happens less and less.
Today's announcement comes not long after the Government moved to implement a digital services tax – a 3 or 4 per cent tax on the revenue of digital giants such as Facebook and Google.