King Country school bus drivers are walking off the job on Tuesday morning.
Sixteen drivers in Te Awamutu and Otorohanga are striking amidst claims of failed pay negotiations.
First Union claims the semi-retired bus drivers are poorly paid and asking for a living wage, and spokesman Jared Abbott says they feel undervalued.
"Bus drivers are so poorly paid - and school bus drivers especially," he says.
"This is the most precious cargo we have, our children. To pay them within a few cents of the minimum wage for the work they do."
But Go Bus is defending its pay negotiations, insisting workers have just been given a generous pay increase.
"Recently those drivers received a very generous increase from the company, well in excess of inflation," CEO Nigel Piper says.
"They received that in March, we're somewhat perplexed."
Mr Piper says the company can't afford to pay all of their employees a living wage.
"[The] cost of us to move to the living wage across the company is in excess of $13.6 million per annum," he says.