While inflation was largely due to global issues, and set to worsen due to Russia's invasion of Ukraine and its impact on oil prices, Luxon said it effectively meant Kiwis were facing higher tax bills.
"The facts are stark – we have a cost-of-living crisis in New Zealand," Luxon told an audience in Botany, Auckland.
"Inflation is at a three-decade high," he said.
"With prices rising twice as fast as wages, Kiwi families are worse off than they were 12 months ago.
"Food price rises are the highest in a decade, petrol has hit more than $3 a litre, and rents are through the roof."
Deputy Prime Minister and Finance Minister Grant Robertson meanwhile called Luxon's approach the "same tired old story".
"The maths just does not add up. Christopher Luxon wants to cut taxes, reduce debt, and keep on spending.
"They need to front up to Kiwis and say which health, education and housing services they will slash to make that happen."
Speaking to media, Luxon denied their policies would cut services. The tax bracket adjustment would be funded out of Robertson's already-announced $6 billion in extra spending for this year's budget, costing $1.7b.
It was better for Kiwis to decide how to spend that money themselves rather than politicians, he said.
They were not talking about "austerity" but making sure spending was done "wisely and prudently", he said.
Under their tax bracket adjustment Luxon said someone on the average wage would be better off by $870 a year.
In his speech Luxon was critical of the Government, saying it was "all spin and no action".
He railed against Labour policies, including Three Waters, said the Government was "deeply suspicious of business", yet led a public sector that could not deliver.
He also announced National would reshape the social safety net, refocusing on the social investment approach developed by former prime minister Bill English.
Robertson said Luxon's speech addressed none of the major challenges, including climate change and the ongoing pandemic, and to fund it would see health, education and housing services slashed.
"Luxon's proposals will just make things worse. There will be more congestion on Auckland's roads, it will be harder for first-home buyers to buy a house and those on low incomes will fall further behind."
New Zealand had one of the "strongest and resilient economies in the world", Robertson said.
"Unemployment is at a record low and our exporters are benefiting from higher prices for their produce.
"We are in a strong fiscal position, with lower-than-expected deficits and debt levels well below that of other countries we compare ourselves against."
The Taxpayers' Union called Luxon's proposals "modest" and said Robertson should update the tax brackets for the past 10 years, covering inflation from when they were originally set.
The Council of Trade Unions chief economist Craig Renney meanwhile said the tax cuts and policy reversals would only benefit high-income earners, pump up inflation and make the housing crisis worse.
"Luxon hasn't provided any analysis within his speech to show how his proposed grab-bag of cuts will lead to lower inflation. Nor has he shown what would be cut to pay for it."
