"Our payroll people today are managing a massive amount of money, managing financial risk, managing an incredibly complex and quite frankly not-fit-for-purpose piece of legislation that doesn't always accord with the guidance that goes with it.
"They're managing a regulator (MBIE) who is also on a learning curve. They're managing pieces of software that often don't talk to each other. Often time-and-attendance software isn't linked to the payroll software," Hall said.
"In many organisations they're also managing a whole range of different contracting requirements and a whole range of workplace practices.
"Put all that together and you pay someone $30,000 to $40,000 and call them a wages clerk and you wonder why you get a problem."
A Government taskforce reviewing the 2003 Holidays' Act is due to update its latest findings and progress any day. The taskforce's final report is due out in June with any new resulting legislation at least two years away.
Meanwhile the Government, through MBIE, Ministry of Business, Innovation and Employment, continues its switch from reactive policing of the Holidays' Act (responding to complaints) to proactive and staff remediation bills for underpaying companies and organisations have ranged from thousands of dollars to around $40 million for the NZ Police.
Hall said even bigger remediation costs are potentially looming for other government sectors. But while the taxpayer would pick up the underpayment bill for the public sector, small or medium business could go under.
A large number of New Zealand employers were affected by the problems caused by "legislation in 2003 based on a 1981 Act", she said.
Most affected were employers in industries with highly variable hours, or paying commissions, allowances and other add-ons.
"This is where you need an actively managed payroll. Instead, you get a company which purchases software and thinks they're getting compliance ...
"To my mind business in New Zealand needs to rethink the payroll function - what that job looks like, the size of it, what sort of person you want there, what training and support you are going to provide for people in there."
Hall said new IRD reporting requirements would add another dimension.
"We have two different regulators and two different statutory regimes around tax and the Holidays Act. Just because you are giving information to IRD doesn't mean MBIE will automatically get it.
"And MBIE has a resourcing problem. They're auditing and they've embarked on a proactive regime as opposed to the previous reactive one - that's fine but it's taking them a while to chew through some of these audits. With quite big complex companies you're looking at a two-to-three-year process to get all the stuff unwound which results in some pretty huge costs to a company.
"The problem is, if you have an error in say an annual leave calculation, it impacts on the gross earnings amount you use to calculate the subsequent annual calculation, and on it rolls and rolls."
Latest available figures from MBIE show that between July 2012 and September this year it audited 165 entities and completed 144 audits. Most gross payouts were in the $600 to $1200 range.
The amount of arrears paid was $18.9 million and the number of employees paid arrears was 34,000. Eight employees had been paid $1001 or more. The range of average gross payments per affected employee per employer was $29 to $4100.
These figures did not include NZ Police cases or remediation cases under "watching" status.
