The Time Act 1974 set the rules in regard to daylight saving and what an employer needs to paid employees working during that time.
5. Effect of commencement and cessation of New Zealand daylight time on pay and allowances(1) Where, by reason of the commencement of New Zealand daylight time on the day specified in any Order in Council made under subsection (1) of section 4 of this Act, the hours worked by any person on that day are less than the hours he would otherwise have worked, the pay and allowances of that person for those hours shall be an amount equal to the amount of the pay and allowances for the hours he would otherwise have worked.
(2) Where, by reason of the cessation of New Zealand daylight time on the day specified in any Order in Council made under subsection (1) of section 4 of this Act, the hours worked by any person on that day are in excess of the hours he would otherwise have worked, the pay and allowances of that person for the excess shall be calculated and paid at the appropriate rates for work performed in excess of normal hours.
In a nutshell, what this section means is:
When time is put back in April and if the employee works an additional hour they must be paid for the additional time.
When time is put forward in September, and if the employee works an hour less, they must be paid for the hour lost.