By Brianna Mcilraith of

For more than 70 years June's first public holiday was known as Queen's Birthday - but just because it has a new name, it doesn't mean the rules have changed.

What is King's Birthday?

Despite King Charles' birthday being in November, a public holiday on the first Monday of June every year commemorates the day, which is 5 June this year.

This is because it is traditional for British monarchs who are not born in summer to celebrate twice. They get one celebration on their actual date of birth, and then an official one in the British summer, including the Trooping the Colour parade.

The tradition was started by George II in 1748, who was also born in November. He tied his celebrations in with the Trooping the Colour because it was too cold for his own celebratory parade.

King's Birthday was formerly known as Queen's Birthday until the death of Queen Elizabeth II in September last year.

So what will be open on King's Birthday?

By law, all shops must close for three-and-a-half days a year - Christmas Day, Good Friday, Easter Sunday, and until 1pm on Anzac Day.

There is no obligation for retailers and cafes to be closed this weekend, although they can if they wish.

Big retailers and supermarkets will stay open, including malls, but some may be operating with shorter hours.

A lot of big retailers also hold sales throughout the long weekend.

Meanwhile, most council-run libraries, swimming pools and attractions will be closed on King's Birthday.

If you are required to work on a public holiday you'll be paid time-and-a-half, and may get an alternative day off.

But will I be charged a surcharge?

Retail NZ chief executive Greg Harford said public holidays were an expensive day to be a business and King's Birthday was no exception.

Because of this, businesses such as cafes are entitled to charge extra on a public holiday when they have a justifiable reason to do so.

"These are big costs, and some businesses which are staff intensive will often surcharge so that they are not out of pocket when they open their doors on a public holiday," Harford said.

Often businesses charge a surcharge on public holidays to cover their staff being paid extra.

If a business does charge a surcharge, it must have clear signage or communicate this to customers before they pay.

If customers believe they've been misled about a surcharge, they can complain to the Commerce Commission.

Is anything else affected?

Those receiving payments from Work and Income will get their money a little earlier this week thanks to the public holiday.

If your pay day is a Tuesday, you'll instead be paid on Saturday, 3 June, as payments will not be processed on Monday.

* This story originally appeared on Stuff. and then published by RNZ.