New Zealand's "shadow economy" is worth over $20 billion and the tax that is lost from it is equivalent to 44 per cent of the country's health budget, a European anti-tax dodging group says.

Figures from the European Network on Debt and Development show New Zealand comes in at number 51 of 145 countries in terms of the cost of tax abuse. Australia is 19th.

New Zealand's shadow economy makes up 12.4 per cent of gross domestic product (GDP). The total tax lost each year from the shadow economy - that is from people who evade tax or move it to tax havens - is $7.1b. This is just behind Bulgaria and just ahead of Azerbaijan.

The network says this amounts to 44 per cent of the total health budget of New Zealand.

New Zealand's shadow economy as a percentage of GDP is similar to China and the United Kingdom.

Total tax evasion is in excess of US$3.1 trillion ($4 trillion) or about 5.1 per cent of global GDP.

The biggest shadow economy in absolute terms is that of the United States at just over US$1.2 trillion.

It is followed by Brazil, Italy, Russia, Germany, France, Japan, China, United Kingdom and Spain.

When compared with the size of tax evasion compared with national health budgets, Bolivia comes top with lost tax equivalent to 419 per cent of medical care.

It is followed by Russia and in third place, Papua New Guinea on 305 per cent.

The network claims multinational tax dodging is the main reason why developing nations stay aid-dependent.

The network says the issue of tax collection is rising fast up the political and social agenda, as countries across the world make deep cuts in public spending and increase taxes in ways that hurt the poor and the middle classes the most.

"This new research demonstrates how important it is to tackle tax evasion and the tax havens that help wealthy individuals and organisations escape from contributing to the services that directly benefit them - from the health and education systems that support their workforces, to the roads that ship their goods to markets, to the courts of law that enforce their contracts or to the police who protect their property."

Its data covers 98.2 per cent of the world gross domestic product and 92.4 per cent of the world's population.