"The unions have not accepted the latest pay offer from NZ Bus and have not agreed to withdraw the strike notice for not collecting fares. NZ Bus advises that drivers who continue participating in the strike will be suspended from tomorrow."
NZ Bus operates some of Auckland Transport's busiest routes along Dominion, Sandringham, Mt Eden and Manukau Roads, as well as other routes across the wider Auckland region and the LINK services.
The strike could last more than two weeks.
NZ Bus, the principal bus company for Auckland, said it had been advised by FIRST Union and the Tramways Union that its members proposed taking strike action between 4.30am tomorrow and 4am on December 24.
The drivers - about 800 - intended not to collect fares or work the electronic ticketing systems.
Chief executive Barry Hinkley said "if the drivers do not collect fares, then we cannot afford to operate the buses".
The company would be going into mediation with drivers on Monday.
A full list of affected services will be available on AT's website, Facebook and Twitter.
Commuters were encouraged to check for updates before they travel.
Bus services operated by other companies would continue as scheduled, as will train and ferry services.
AT apologised for the inconvenience.
Meanwhile, Statistics New Zealand released figures on the make-up of Kiwi bus drivers.
On average, they are the oldest workers of any key industry and are among the most loyal employees.
The average age of bus service workers was 54 in the year ending March 2018, the annual release of linked employer-employee data (LEED) showed.
Nationally, the number of people in the bus service industry rose from 8980 in 2008 to 10,400 in 2018. The 2018 Census showed there were 8874 bus drivers nationwide.
"The average age of bus service workers is eight years older than the age for the next highest industry and 24 years older than millennials working in hospitality," LEED manager Alan Bentley said.
"The baby boomers working on the buses also tend to stay in the job for longer than they would in most other industries," Mr Bentley said. "Almost nine in 10 bus drivers stay in the bus service industry for at least one year. In terms of worker loyalty, boomer bus drivers are okay."