If you are thinking of pulling a sickie today to enjoy a four-day weekend, think again.

With Anzac Day falling on Tuesday, the temptation to come down with a headache or diarrhoea will be tempting a lot of people, but you do so at your peril, says employment expert Max Whitehead.

It's a big risk to call in sick today and highly likely you will be asked to produce a medical certificate, which employers can ask for under the Holidays Act if there are reasonable grounds for suspicion, Whitehead said.

However, under the law your boss would need to pay for the doctor's visit.

Really sensible employers and employees will use that time as annual leave

What's more, Whitehead and Auckland Chamber of Commerce chief executive Michael Barnett, said social media make it easy to get caught out.

"The eyes are on you all the time," Whitehead said.

Barnett said a lot of companies will give staff time off today so long as it does not disrupt business too much. He is going to Edgecumbe to help with the clean-up after the floods.

Employment lawyer Helen White said there had always been a phenomenon of Mondayitis but it was sensible for employers to give staff time off tomorrow with Anzac Day falling on Tuesday.

"We have to start responding to how busy people are. They are all working, they have got their kids. It's Anzac Day and school holidays. Really sensible employers and employees will use that time as annual leave," White said.

An ANZ spokesman said customer facing roles, like branch and contact centre staff, would be working today but a lot of head office types in the main centre will be taking leave.