IRD number and KiwiSaver: what Americans in New Zealand need to know

Getting an IRD number takes a couple of days. Deciding what to do about KiwiSaver, as a US citizen, can take a lot longer.

The short version

• Get your IRD number as a "new arrival" through myIR, using your visa details. Approved numbers come by text or email in 2 days, and it's free [1][2].
• You can join KiwiSaver only once you're a citizen or resident. Work, student and visitor visa holders can't join [3].
• Once you're in, the default is 3.5% of your pay, matched by at least 3.5% from your employer, and the government adds 25 cents per dollar up to NZD 260.72 (about USD 147) a year [4][5].
• The IRS hasn't said how KiwiSaver should be taxed. Preparers debate foreign trust and PFIC treatment, and the US–New Zealand tax treaty doesn't shelter it like a 401(k) [6][7].
• You can opt out only in a narrow window: between day 14 and day 56 after starting a job where you were auto-enrolled [8].

USD conversions in this guide use the Federal Reserve H.10 rate of October 30, 2026 (NZD 1 = USD 0.5637), rounded. KiwiSaver's US tax treatment is contested; this is general information, and a US expat tax preparer who knows New Zealand can check your situation.

Step one: your IRD number

An IRD number is New Zealand's tax ID, roughly the local version of your Social Security number for tax purposes. You need it to open a bank account, start a job, join KiwiSaver and file taxes, and you keep it for life [1].

Applying as a new arrival

Inland Revenue has a fast-track process for people who've just arrived. It checks your identity with Immigration New Zealand, so you don't send the same documents twice [2].

1. Register a personal myIR account with Inland Revenue.
2. Gather your details. On a work or student visa: your passport details, your Immigration New Zealand application number and your most recent overseas tax number, if you have one. On a resident visa: passport details and your application number [2].
3. Apply before your visa's "arrive by" date. That date is also the deadline for using the new-arrival process. Miss it and you'll apply through the slower "living in New Zealand" process [2].
4. Wait about 2 days. If you're approved, your number comes by text or email [2].

There's no fee [1]. Give the number to your employer and bank right away so you're taxed at the correct rate.

How KiwiSaver works

KiwiSaver is New Zealand's voluntary-but-nudged retirement savings scheme. Think of it as a 401(k) with auto-enrollment, an employer match baked into law, and a small government top-up.

Who can join

You can join if you're a New Zealand citizen, or entitled to live in New Zealand indefinitely, and you live or normally live in New Zealand. You can't join on a temporary, visitor, work or student visa [3]. So most Americans first meet KiwiSaver when they get residence and start a new job, because employers auto-enroll eligible new hires [3].

Contributions

You can change your rate once every 3 months, unless your employer agrees otherwise [4]. Self-employed members set contributions with their provider [4].

The government contribution

You qualify if you're 16 or older, earn NZD 180,000 (about USD 101,500) or less in taxable income, and live mainly in New Zealand. It's prorated for the days you're eligible, and your provider claims it for you [5].

Getting the money out

KiwiSaver is locked in until retirement age, with exceptions. The main one is buying a first home: after 3 years of membership you can usually withdraw most of your balance, leaving NZD 1,000 (about USD 564) in the account [5].

How the IRS may treat KiwiSaver

Here's the hard part. A 401(k) gets special treatment because the Internal Revenue Code says so. A foreign retirement plan gets similar treatment only if a treaty provides it.

What the treaty says

The 1982 US–New Zealand income tax treaty has a saving clause in Article 1(3): the US may tax its citizens "as if the Convention had not come into effect" [7]. The exceptions in Article 1(4) cover social security payments under Article 18(1)(b), but not private pensions [7]. The treaty's pension article covers how pensions are taxed when paid; nothing in it lets a US citizen defer US tax on contributions or growth inside a New Zealand plan [7].

The competing views

Because the IRS hasn't ruled on KiwiSaver, preparers use different frameworks. In general terms:

1. Foreign grantor trust. You're treated as owning the fund's assets and taxed on its income each year. This often brings Forms 3520 and 3520-A into play.
2. Employees' trust (Section 402(b)). Employer contributions are taxable compensation when they vest. Growth is generally taxed at distribution for most participants.
3. PFIC look-through. KiwiSaver funds are typically invested in pooled funds. If you're treated as owning those funds directly, they can be PFICs, the punishing US regime for foreign mutual funds, which can mean an annual Form 8621 for each fund [9].

The government contribution adds another wrinkle: some preparers treat it as taxable income. Employer contributions are usually covered by foreign tax credits from your New Zealand income tax, but PFIC calculations don't play nicely with credits.

Reporting

Rev. Proc. 2020-17 covers trusts "established and operated exclusively or almost exclusively" for retirement benefits, with conditions in section 5 [10]. Many preparers think KiwiSaver fits, but check yours. The exemption doesn't touch your FBAR or Form 8938 [10].

Should you opt out?

For many Americans, the honest answer is "talk to your preparer first, and fast." The opt-out window is short.

How opting out works

• If your employer auto-enrolled you, you can't opt out in the first 13 days. You can opt out from day 14 to day 56 [8].
• You must opt out again every time you start a new job [8].
• Late opt-outs, up to 3 months after Inland Revenue gets your first contribution, are allowed only in specific cases, such as your employer not giving you the KiwiSaver information pack (KS3) within 7 days [8].
• If you joined directly with a provider, you can't opt out. You might be able to take a savings suspension instead [8].

Weighing it up

Opting out avoids the reporting mess and possible PFIC treatment. Staying in gets you the employer's 3.5% and the government contribution, which is real money over a career. Some Americans stay in and pick a provider and fund structure their preparer is comfortable with; others opt out and save in other ways. Neither choice is wrong, but the default of doing nothing is a choice too.

If your partner is Australian and you might end up across the Tasman, our sister site ExpatCooee explains how super works while you live overseas.

KiwiSaver comes up often in our community group for Americans in New Zealand, but the answer depends on your fund, your income and your filing history.

Sources

1. IRD numbers, Inland Revenue
2. New arrival to New Zealand: IRD number application, Inland Revenue
3. Joining KiwiSaver, Inland Revenue
4. KiwiSaver employee contributions, Inland Revenue
5. KiwiSaver benefits, Inland Revenue
6. Comparison of Form 8938 and FBAR requirements, IRS
7. US–New Zealand income tax convention (1982), IRS
8. Opting out of KiwiSaver, Inland Revenue
9. About Form 8621, IRS
10. Instructions for Form 3520-A (Rev. Proc. 2020-17 exemption), IRS

Keep reading

• New Zealand taxes for Americans: how they fit with your US return
• Banking in New Zealand as an American
• PFICs: why foreign funds hurt Americans
• 401(k) and IRA when you live abroad