The government agency which sets pay rates for the country's mayors is for the first time to stipulate the packages are based on the job being a full-time role.
However, the Remuneration Authority said there would be no new rules or guidelines prohibiting mayors from taking on work outside of their civic duties.
Pay packages for the country's civic leaders range from the $270,000 the Mayor of Auckland, Phil Goff, pockets to $52,000 paid to the mayor of the Chatham Islands.
Remuneration Authority chairwoman Fran Wilde said up until now its policies had not spelt out the packages - which often include use of a mayoral car - were based on a full-time job.
"We take it that mayors' jobs are full time, however, and most mayors with whom I'm familiar with, work pretty much every day, most of the weekend and most nights during the week as well," Ms Wilde said.
The new policy, which begins this week, was the result of an internal review.
Mayors who wished to continue doing work outside of their civic duties would still be able to, Ms Wilde said.
"We don't have rules because we're not the employer. The employer is the people of the district who vote in a mayor and I guess if they don't think a mayor is giving them good service they will vote that mayor out."
Local Government New Zealand president Dave Cull, who is also the mayor of Dunedin, said there were plenty of mayors around the country who continued to have business and professional interests outside of their civic duties.
"I think the question to ask in any situation is: Is the job being done? Is the mayor's job being done? Are all the responsibilities of the mayor being fulfilled? And if they are, what's the problem?" Mr Cull said.
"Clearly if you asked my wife if I worked full time she'd just laugh and say 'and weekends as well'."
Despite this, Mr Cull said Local Government New Zealand considered most mayoral posts were full-time roles and did not leave a lot of time for anything else.
"Most mayors of cities and towns and districts or anything like that ... it's a full-time job and could be a seven-day, 24-hour job if you wanted it to be. But clearly no one's going to let it dominate their life to that extent."
New Plymouth Mayor Neil Holdom says his civic duties are a priority over his consultancy job. Photo: RNZ / Robin Martin
New Plymouth Mayor Neil Holdom, 46, stepped down from his executive position at lines company Powerco when he was elected in 2016.
Mr Holdom said he had since started a strategic planning consultancy and on average did about six hours' work for it a week.
The father-of-three was paid $135,000 for being mayor and said he worked between 50 and 55 hours a week in that role.
"It's my top priority. This week's a good example [I'm working] seven days and two late nights," Mr Holdom said.
"I haven't done any consulting work for the last five weeks but over summer when things are quiet, yeah, I pick up a bit of work," he said.
"And I think it's about balancing the requirements of the role and doing the job justice and I believe that I'm doing that."
Mr Holdom believed it was important for a mayor to retain ties with the private sector.
"I think it's important to bring a commercial perspective to council. I don't want this job to swallow me up so that I become just a purely political person," he said.
"I think it's good to have the reality of trying to run a small business."
Two hours down State Highway 3, Whanganui Mayor Hamish McDouall pocketed $112,000 for the role.
He chose to give up his legal practice when he was elected in 2016.
"I tried to be a councillor and a lawyer at the same time and I realised I couldn't do either justice so when I became mayor it was full time," Mr McDouall said.
"I'm probably working say during a light week about 50 hours."
Whanganui Mayor Hamish McDouall says he gave up on being a lawyer and mayor at the same time to give the role his undivided attention. Photo: RNZ / Robin Martin
Mr McDouall said he wanted to concentrate on being the best mayor he could.
"If you're trying to lead some transformative change or if there's a lot of money floating around as there is around the Provincial Growth Fund, you really need to put all your energies into grasping these opportunities."
On the streets of New Plymouth, opinion was divided over whether a mayor should take on outside work.
"Well generally you'd think that being a mayor is a full-time job," former teacher Mervyn Chivers said.
However, Lynne While had a different take.
"Retaining some interest in your profession is perhaps a good idea," Ms While said.
While another resident Daniel Morgan thought people focused too much on the money.
"Time's the most important thing in the world. Money can't buy you time with your family and things like that," Mr Morgan said.
The Remuneration Authority will publish new pay packages for New Zealand's civic leaders later this month and will be back dated to 1 July.