Every Kiwi house and commercial property may need to be valued en masse by a computer programme under a capital gains tax, leading to warnings of a flood of objections from homeowners.

The mass valuation - already termed "V-Day" by pundits - could take place on April 1, 2021, the proposed date when the Government might bring the tax in.

While family homes would be exempt, most people would likely pay a CGT tax rate of 33 per cent on affected investment properties, farms and baches.

The tax would be charged on the gain in price a property sells for compared to its value at April 1, 2021.

With an estimated 1.88 million private dwellings in the country - not counting businesses - valuers CoreLogic have suggested the mass valuations be done by an automated process, similar to how councils value ratepayers' homes.

One Roof Property Commentator Ashley Church joined The Weekend Collective to share her expert advice over getting your head around the proposed tax.

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