Museums are hoping for an exemption to a new Fire Service levy because of their role as kaitiaki, or guardians, of important parts of the country's heritage and culture.
The Fire and Emergency Bill, currently before a select committee, will change the way the levy is calculated.
Some museums believe their payments could triple, by tens of thousands of dollars in some cases.
Museums Aotearoa, which represents more than 200 museums and galleries, is worried payment will be based on the value of collections, rather than buildings and fittings.
Executive director Phillipa Tocker said that was problematic because many museums are small, or relatively poorly funded, compared to the value of the items they hold.
"We're arguing that heritage and cultural collections that are held as kaitiaki for the public should be exempt from that levy," she said.