公立幼稚園、小学校のスクールdonationは寄付ですので、払う払わないは個人の自由です。そのdonationを払った場合、IRDに申請することより、一部がtax credit として、総納税金額が軽減されます。以下の条件にあてはまる必要があります。

You can claim a tax credit if you:

made a donation of $5 or more to an approved donee organisation where the payment is voluntary and there is no identifiable direct benefit to you or your family in return for making the payment

earned taxable income (such as salary or wages, benefit, NZ Super, self-employed income, interest and dividends) during the year you're claiming for
were resident in New Zealand at any time during that tax year,

and
are an individual (not a company, trust or partnership)

Donation receipts
You need receipts to show that you made a donation of $5 or more to:

approved donee organisations
approved overseas aid funds (approved as a donee organisation by the New Zealand Parliament)
state, state integrated schools and partnership schools kura hourua.
other schools who have been approved as donee organisations (the payments must be "donations"
parent-teacher associations (the payments must be "donations".


Valid receipts
Your receipt(s) must contain:

the name of the donor(s)
the amount and date of the donation
a clear statement that it is a donation
a clear statement at the top of the page if the donation is a payroll giving donation
the signature of an authorised person, and
an official stamp with the name of the approved donee organisation.
The word “copy" or “replacement" should be clearly shown on any replacement receipt.



Maximum amounts you can claim
The total donations you claim can't exceed your taxable income for the year. If they do, you can claim donations up to the amount of your taxable income.

The maximum tax credits you can claim are set out below.

You can claim the lesser of:

33.3333% of the total donations you've made, or
33.3333% of your taxable income.
Go to Greater tax incentives for charitable donations for the new thresholds.