Small businesses say an employment law change that's largely gone under the radar has huge implications for employers.

Chief Executive of the Small Business Voice Max Whitehead said changes to the Employment Relations Act now required every employer to account for all its employees hours of work including salaried workers.

He said the new law insists that all employers keep an accurate record of their salaried employees hours worked each day, including their start time, finish times, any non-paid breaks taken, and the days worked in each pay period.

Mr Whitehead said this is imposing more compliance costs on businesses.

"It really is going to impact on probably tens of thousands, if not hundreds of thousands of New Zealanders. For small employers this is going to be hell on earth. It just means a lot more time consumed in just gaining information to please the Government."

"It will cost, and again, it will come back to the consumer. I'm really am surprised that this government's gone and imposed more compliance costs. We've got the health and safety laws coming into being which probably have good justification. For this one, I've got some question marks on it."