The AM Show sports reader Mark Richardson says Labour's tax policy is "disingenuous", echoing claims from other politicians it won't raise enough to cushion the COVID-19 blow.
If re-elected, Labour says it will create a new top tax bracket for those earning over $180,000 of 39 percent.
ACT leader David Seymour said on Wednesday the tax change "won't raise anywhere near the $500 million Labour says it will".
"Jacinda Ardern likes to say we're all in this together, but Labour is picking on a small group of New Zealanders to fund the COVID-19 recovery," Seymour said.
Richardson said while he accepts the country is in a situation where he will have to pay more tax, he found Labour's policy "completely and utterly disingenuous".
"It's not going to raise enough money, for a start," he told his co-hosts on The AM Show. "It's cowardly because they're not prepared to ask for more money from those people they believe who vote for them."
The proposed tax rate remains lower than the likes of Australia, where people pay 47 percent if they earn more than $180,000.
Richardson believes Labour's proposed policy is a political move "to grab the middle ground", motivated by "jealousy"
But Finance Minister Grant Robertson said New Zealanders want "certainty and stability".
Under this proposed policy, Labour won't make further increases on any income tax, he said.
"This policy is about maintaining investment in important services that are so crucial for New Zealanders like health and education, while keeping tax rates the same as they are now for 98 percent of people," he told reporters on Wednesday.
"The new rate will cost $23 a week for an individual earning $200,000, but it will make a big difference to the country's ability to maintain the investments needed for the economy to bounce back."
Fuel taxes would also not be increased should Labour win another term, the Finance Minister said.
Labour revenue spokesperson Stuart Nash said economies grow strongly when higher earners are paying tax rates above 39 percent.
"When New Zealand previously had a 39 percent top rate, it certainly didn't stop GDP from growing at annual rates of 3 percent and 4 percent," Nash said.