Internal Affairs Minister Brooke van Velden said she was assured this was enough to fund essential frontline work.
“It is important that Kiwis are not paying more than necessary to ensure Fenz is resourced to maintain high standards of frontline services,” she said in a statement.
She has also told Fenz to find savings of $60 million by 2029 so it can build up its reserves.
Fenz is 97% funded by levies, which the insurance industry is unhappy about and has called for the Crown to fund the service from its main pot.
Fenz earlier argued it needed the 12.8% rise because it was “urgent and cannot wait”.
“Our operating costs have increased, and we face immediate funding shortfalls,” it said in a report in April.
It has a number of fire stations that need upgrades, seismic or asbestos work, and an ageing fleet of large fire trucks prone to breakdowns.
It earlier forecast its operating costs to rise to $748m next year, plus nearly $90m in capital costs. Its operating costs in 2016 were $423m. It also has a $75m Crown loan it has to pay back.
The 12.8% rise has relieved some of the pressure.
The minister in April asked Fenz’s board for evidence it needed the subsequent 5.2% increase; she earlier refused RNZ’s request to see related briefings.
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