The scrutiny of the National Party's tax plan is forcing the party to dig in with its assurances that it's credible.
It comes as the governing Labour Party, tax and trade experts, dispute the legitimacy of several elements - especially its foreign buyer tax.
National's finance spokesperson Nicola Willis yesterday told TVNZ's Q+A that it sought advice about whether the foreign buyer tax would breach New Zealand's tax treaties after it released the policy last week.
The New Zealand Initiative chief economist Eric Crampton spoke to Corin Dann.
