A new report is recommending the Holidays Act be overhauled.
It wants the current four formulas used to calculate leave rationalised into a single formula and employees to be given the option to swap days off for cash.
The review, by law firm Simpson Grierson, asked 162 employers how they rate the usability of the Holidays Act.
Forty-two percent said it was difficult or very difficult to use and 52 percent of those asked said staff should have the option of cash in exchange for annual leave.
Simpson Grierson senior associate and co-author of the report Rebecca Rendle says the Act needs some fundamental changes.
She says 87 percent of respondents said it would be easier to have one formula to calculate leave.
Ms Grierson says having four formulas used to calculate leave makes it difficult to know which formula to apply and whether it is being applied correctly.
She says a second recommendation was that accrual and payment of leave should be in hours, rather than in the current days and weeks.