An employment lawyer says the Holiday's Act needs to be streamlined down to just one rule.

Ian Lees-Galloway is today announcing a panel to review the legislation - which legal experts say require seven different calculations to work out employee pay.

Simpson Grierson employment lawyer Phillipa Muir told Mike Hosking it's been too difficult for too long.

"I believe we should be going to one formula for all types of leave. It'll make it much simpler because there are unintended consequences for employees whose employers are getting it wrong for no fault their own."

LISTEN TO PHILLIPA MUIR TALK WITH MIKE HOSKING ABOVE