Jacinda's going to find out the hard way about tax changes or whatever she wants to call them. They won't work but she will become a very upopular prime minister in the process. Tax changes are more successful if implemented by stealth.
as eminent economist John Kay says "....all tax systems are encrusted with barnacles, the product of the wheezes of politicians and the power of lobbies. But the results of such approaches to tax reform are usually disappointing."
If Jacinda needs more money in a hurry just increase the GST rate to 20% - easy peasy