Auckland's taxi companies say they will put on extra cabs to help cope with thousands of revellers leaving central city bars and clubs at 4am next week.

New drinking laws begin on December 18 and Auckland Council expects tens of thousands in town on December 20 - the last Friday before Christmas.

Sweeping changes to the Sale and Supply of Liquor Act restrict all-night drinking establishments with new maximum trading hours of 8am-4am for bars, clubs and restaurants.

Auckland Council alcohol licensing manager Rob Abbott said preparations are well advanced for the new restriction which affects up to 300 on-licence establishments.

"Hopefully it will go smoothly. We have to wait and see. We have to plan for the worst and hope for the best."

Tens of thousands of revellers would be on the streets in the early morning and getting them home at that time had called for extra transport measures.

Auckland Co-op and Alert companies told the Herald they had no problems rostering extra cab drivers for the early morning rush.

However, council officials said they realised not all patrons could afford a cab fare so Auckland Transport would offer options available to late night patrons in the city. Buses were currently available until 3.40am from Britomart.

For the weekend of December 21-22, the Northern Busway will run throughout the two nights and trains will run from 5am with hourly services for the western, eastern and southern to Manukau and southern to Papakura lines.

Councillor George Wood said people were confused about the new 4am closing time, thinking premises with licences to 3am would now stay open an hour later, but he said all licensed premises with shorter hours than 8am to 4am remained bound by their current licence.

Alcohol crackdown

The main changes to liquor laws under the Sale and Supply of Alcohol Act which kicks in on December 18:

• $5000 infringement notices for bar owners if intoxicated people are in their premises.

• On-licences can open between 8am-4am and off-licences can open 7am-11pm.

• Licences and manager's certificate cancelled for five years if offences committed three times in three years.

• Managers could be fined up to $4000 (and other staff fined up to $2000) for being intoxicated on duty.

• $250 on-the-spot fines for drinking in a public place or using a fake ID.

• Except within licensed premises, you cannot advertise free alcohol, promote discounts of 25 per cent or more, or offer customers free goods, services or opportunities to win prizes if they purchase alcohol. The penalty is a fine of up to $10,000. A business licence may also be suspended or cancelled.

• Bars will be required to provide free drinking water.

• Dairies and stores selling convenience foods (for example, confectionary, ready-to-eat takeaways and snack food) cannot sell alcohol.

• Alcohol displays and promotions can only be in a single area of a store.

• People holding an event that requires a special licence must now apply at least 20 working days beforehand.

• You can only supply alcohol to a person under the age of 18 years if you are their parent or legal guardian, or you have express consent from their parent or legal guardian or the young person is married, in a civil union or living with a de facto partner. The penalty for breaching the law is a fine of up to $2000.

• Anyone supplying alcohol to a person under the age of 18 years must do so responsibly, making sure food and non-alcoholic drinks are available and arranging safe transport or face a $2000 fine.

• Communities have more say on alcohol licensing, such as determining maximum trading hours in their area, limiting the location of licensed premises near certain facilities such as schools and widening the grounds for objecting to licences.