Part-time versus full-time: the pro-rata maths and what you give up

Pro-rata pay, leave and KiwiSaver

Pro-rata means in proportion. A full-time salary of $80,000 at 0.8 FTE, four days a week instead of five, becomes $64,000. Your hourly rate stays the same, about $38.46 on a 40-hour week, so you are paid the same for each hour; you just work fewer of them.

Leave follows the law rather than the fraction. Employment New Zealand says permanent part-time employees have the same minimum entitlements as full-timers:

• Annual holidays: four weeks after twelve months, and a week off is a week of your normal days, so four weeks off at four days a week is sixteen working days, paid at your ordinary weekly pay or your average weekly earnings, whichever is higher.
• Public holidays: a paid day off when the holiday falls on a day you would otherwise work. If you never work Mondays, a Monday holiday does not give you an extra day.
• Sick leave: ten days after six months, not pro-rated. Someone working three days a week still gets ten days.

The Employment Leave Act 2026 will replace the Holidays Act on 6 August 2028, with new rules for leave. Until then, the current rules apply.

KiwiSaver is deducted from every pay at the same rate, so both your contribution and your employer's fall in step with your pay. At 3.5%, the employer's contribution drops from $2,800 a year to $2,240 in the example. That is a real, if small, cost of going part-time.

Why 0.8 FTE keeps more than 80% of take-home pay

New Zealand's income tax rises in steps. At 2026/27 rates, income is taxed at 10.5% up to $15,600, 17.5% to $53,500, 30% to $78,100, 33% to $180,000 and 39% above that. When you cut your hours, the income you lose comes off the top, where the rate is highest.

Giving up $16,000 of salary costs $10,303 of take-home pay, about 64 cents for each dollar, because that income was taxed at 30% and 33%. With a student loan the effect is a little stronger, because repayments are 12% of income over the threshold, applied in each pay period: the four-day week keeps 84.1% of full-time take-home pay. The fifth day was paying you about $396 a fortnight after tax.

What shrinks that should not

The risk in going part-time is not the pay, which you can calculate, but what quietly shrinks with it. Two things to watch:

• Scope. A four-day week should come with four days of work. If the job stays the same size and you do it in fewer paid hours, you have taken a pay cut. Agree in writing what comes off your plate, and who picks it up.
• Progression. Part-time staff can be passed over for promotion, stretch projects and pay rises, often without anyone deciding it. Keep your achievements visible, ask how your progress will be judged, and check that pay reviews use the full-time equivalent salary.

Also check your employment agreement for anything tied to full-time status, such as allowances, bonuses or insurance. Some are pro-rated, some stay whole, and some may stop.

The flexible working request

If you are already employed, the route to reduced hours is usually a flexible working request. Any employee can make one from their first day, for any reason. It must be in writing, say it is made under Part 6AA of the Employment Relations Act, and set out what you want to change, from when, and how it could work. Your employer must reply within one month and can refuse only on recognised business grounds, such as being unable to reorganise the work.

A strong request answers the employer's worries before they raise them: how your work will be covered, how you will stay reachable, and a trial of the new arrangement to test it. Our guide to making a flexible working request has a template. If you are coming back after time away, our guide to returning to work after a break covers negotiating part-time hours from the start.

Modelling both on the number that arrives

Before deciding, compare the two options on what reaches your bank account, not the salary. Then set that difference against what the extra time is worth to you, and against costs that change, such as childcare, commuting or a second job.

The Offer Comparer shows two salaries side by side after tax, with or without a student loan, and needs no account. Put the full-time salary in one column and the pro-rata figure in the other, and show pay per fortnight to see the gap as it will arrive.

Keep the record as your hours change