National has accused the Government of using the holiday season to slip a damning report past the public.
The Ministry of Business, Innovation and Employment (MBIE) found that thousands of jobs could be lost or fail to materialise in Labour's plan to boost the minimum wage.
Todd McClay, National economic development spokesperson, says the timing of its release was calculated.
"Whilst the public are on holiday, the Government doesn't want people to notice this. But actually they're moving far too quickly in increasing the minimum wage, and it's having a real impact on small and medium businesses."
The previous year's MBIE review of the minimum wage was created in October, according to metadate on the released document, and released in November. This latest one appears to have been created on December 19, with the webpage saying it was last updated on December 20 - five days before Christmas - and presumably the date it was uploaded.
MBIE's analysis found job numbers would be up about 43,600 in 2020, but could have been about 6500 higher without a minimum wage boost.
But CEO of Mangere Budgeting Services Darryl Evans says it doesn't matter - the number of potential job losses are nothing in comparison to hundreds of thousands who will receive a boost on minimum wage, and National did little to help those struggling.
"Just through this Christmas period, the number of requests for food has been massively high. It's all very well for National to put the boot in, but let's face it - they were there for nine years. You can't sling mud if you didn't make the changes yourself."
Evans says while some jobs may be lost, the good outweighs the bad.
"Families right across the country are struggling. Studies done by organisations like the Salvation Army show that the average family of four on minimum wage, after paying their rent and power are left with around $39 a week to buy groceries."
Finance Minister Grant Robertson has in the past said minimum wage boosts actually create jobs by stimulating the economy.
National increased the minimum wage about 3.4 percent a year when it was last in power. The present Government is averaging 6.6 percent.
Unemployment is at 4.2 percent, slightly up on last year's low of 3.9 percent, which was the lowest in about a decade. The Government boosted the minimum wage $1.20 in early 2019, and will do so again in April 2020, bringing it to $18.90.
"Everybody wants higher wages," said McClay, "but you do that by driving productivity, not just piling costs upon business. Ultimately somebody's got to pay for this, and the people that will lose their jobs are often the ones with the lowest level of skill."
If the Government went for the living wage - currently estimated at $21.15 - MBIE says about 30,000 jobs would be wiped out.