New rules for ministers with babies who are travelling overseas allow them to to take a nanny or carer paid for by taxpayers.
However, Prime Minister Jacinda Ardern says she does not expect the taxpayer to pay for both her partner, Clarke Gayford, and a carer for their baby Neve, NZ Herald reports.
Ms Ardern and Mr Gayford, along with their baby, are travelling to New York today for Leaders' Week for the UN General Assembly.
The prime minister says that she will be paying for her partner's flights, since there are not many engagements for partners.
"There is no spousal programme for this, so we just made a judgment call that we would cover his travel for this trip. He will be going to some things, but he's primarily travelling to care for Neve."
After Ms Ardern became prime minister, the guidelines for ministers' overseas travel were reviewed and changed, reports the Herald.
Now, a minister with young infants is allowed to take someone, other than a partner, to care for that child or for a minister with a disability to take a support person if needed.
Ms Ardern said she never sought for the change and did not intend to use the entitlement for herself, and would only allow it for ministers in "exceptional circumstances."
The prime minister signs off on all ministerial travel overseas, other than to Australia, including deciding whether partners can travel with ministers and who pays for them.
Other ministers with young babies currently include the Green Party's Julie Anne Genter and Education Minister Chris Hipkins, whose partner had a second child this week.
Ms Ardern told the Herald she did not expect to have travel with more than one person, but if there was a situation which required both Mr Gayford and another carer for Neve, she would pay for that extra person out of her own pocket.
"We are playing it by ear. There is no set plan, it's just whether or not she's getting enough sleep, where I am for feeds. They might be with us a lot, they might just be in the hotel,” she said.
"It depends what the jet lag does to them both. She's a good sleeper and we don't know whether that will mean she ends up sleeping a lot in the day rather than the night."
In New York, Ardern is also staying in apartment-type accommodation rather than the usual hotel because basic kitchen facilities were needed for Neve.
Ms Ardern said she had made sure it did not cost more than was usual.