There is confidence the Government will stick to its word when it comes to a capital gains tax.

ACT leader David Seymour is accusing the Government of planning to introduce a capital gains tax by stealth, after Finance Minister Grant Robertson asked Treasury for advice on extending the bright line test.

The test means people need to pay income tax if they sell a second property, that's owned for less than five years.

PWC partner Geof Nightingale told Kate Hawkesby it's politically difficult for the Prime Minister to implement a capital gains tax.

He says Jacinda Ardern has made a commitment to not introduce it, and it's been emphasised by her senior ministers.

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