Filling Out Form 8621 for a KiwiSaver Fund: A Line-by-Line Worked Example
If you are a US citizen with a KiwiSaver fund, the IRS almost certainly treats each underlying fund as a PFIC, and you file one Form 8621 per fund. A three-fund KiwiSaver normally means three forms. Because no major NZ provider supplies the statement needed for the favourable QEF election, most people end up in the default Section 1291 regime, which back-loads tax to the year you sell and adds an interest charge. This page walks through exactly which boxes you complete, with a worked example for a sold KiwiSaver fund.
This is general information, not advice about your specific return, and Form 8621 is genuinely one of the harder US forms to get right. Verify the current form layout and line numbers against the IRS source linked throughout — the IRS reorganised the parts in recent revisions, and old guides still reference outdated part numbers (more on that below). When real money is at stake, run your numbers past a cross-border accountant.
How many Form 8621s do you actually owe?
The rule is mechanical: one Form 8621 for each PFIC you hold. KiwiSaver is not, itself, a single investment — it is a wrapper. Inside your KiwiSaver account you typically hold units in one or more managed funds (a growth fund, a balanced fund, a conservative fund, and so on). Each of those funds that meets the PFIC tests is its own PFIC, and each gets its own form.
A foreign fund is a PFIC if it meets either of two tests for the year: at least 75% of its gross income is passive (the income test) or at least 50% of its average assets produce — or are held to produce — passive income (the asset test). A KiwiSaver fund holding shares, bonds and cash to generate dividends, interest and gains clears these easily. See the IRS Instructions for Form 8621.
| What you hold in KiwiSaver | PFICs | Form 8621s you file |
|---|---|---|
| One fund (e.g. a single Growth Fund) | 1 | 1 |
| Two funds (Growth + Conservative) | 2 | 2 |
| Three funds (Growth + Balanced + Cash/Conservative) | 3 | 3 |
| Three funds, plus a separate NZ PIE managed fund outside KiwiSaver | 4 | 4 |
So a three-fund KiwiSaver = three Form 8621s, each reporting only that fund's value, distributions and any sale. If your provider's annual statement lists, say, a "Conservative Fund" and a "Growth Fund," treat them as two separate PFICs even though they sit under one KiwiSaver login.
Older articles tell you the Section 1291 excess-distribution math goes in Part III. On the current form (Form 8621, Rev. December 2025) it does not. The IRS reorganised the parts: today, Part III is for QEF income, Part IV is for the mark-to-market election, and Part V — "Distributions From and Dispositions of Stock of a Section 1291 Fund," lines 15 and 16 — is where the excess-distribution and interest-charge math actually lives. We use the current line numbers below. Always check the revision date printed at the top of the form you download.
The de minimis exception (and why it rarely saves a KiwiSaver seller)
The IRS lets you skip Part I of Form 8621 if your total PFIC holdings are small: $25,000 or less (or $50,000 or less on a joint return) in aggregate value across all your PFICs at year-end, per the IRS instructions. But there is a hard catch: the exception does not apply in any year you receive an excess distribution from, or recognise gain on the disposition of, a Section 1291 fund.
That is exactly the year a KiwiSaver matters most — the year you withdraw or switch funds and trigger a sale. So the de minimis exception tends to disappear in the precise year you most need to fill out Part V.
Can you make a QEF or mark-to-market election? Usually not.
Form 8621 offers three regimes. They are wildly different in how punishing they are, and which one you can use is not your free choice — it depends on what data you can get.
| Regime | Where on the form | Tax treatment | Realistic for KiwiSaver? |
|---|---|---|---|
| QEF (Qualified Electing Fund, §1295) | Part II, Election A → income in Part III | Annual pass-through of the fund's ordinary earnings and net capital gain. No interest charge. The gentlest regime. | Almost never — needs a fund-supplied statement (see below) |
| Mark-to-market (§1296) | Part II, Election C → Part IV | Annual ordinary income on unrealised gains; some loss relief. | Almost never — needs "marketable stock" |
| Section 1291 (default) | Part V (no election needed) | Tax deferred until distribution/sale, then taxed at top ordinary rates with an interest charge. The harshest regime. | This is where most KiwiSaver holders land |
Why the QEF election usually fails for KiwiSaver
A QEF election is only valid if you can attach the figures from a PFIC Annual Information Statement — a document, supplied by the fund, that breaks out your pro-rata share of the fund's ordinary earnings and net capital gain on a US-tax basis. The QEF income you'd report in Part III comes straight off that statement.
Here is the practical problem: the major NZ KiwiSaver and PIE providers do not produce PFIC Annual Information Statements. They report to you on a New Zealand PIE basis (taxed at your PIR), which is a completely different calculation. No US-format statement, no valid QEF election. You cannot manufacture the numbers yourself — the statement has to come from the fund.
Why mark-to-market usually fails too
The §1296 mark-to-market election is only available for "marketable stock" — PFIC stock that is regularly traded on a national securities exchange registered with the SEC, or on a foreign exchange regulated by a governmental authority (IRS instructions, "marketable stock"). Units in a managed KiwiSaver fund are not exchange-traded shares — you buy and redeem units directly with the provider at the daily unit price. They are not "regularly traded" on a qualifying exchange, so they are generally not marketable stock, and MTM is off the table. (Some NZ-domiciled exchange-traded funds may qualify; ordinary KiwiSaver managed funds typically do not.)
With QEF and MTM both unavailable, you default into Section 1291 — Part V.
Worked example: completing the form for a sold KiwiSaver Growth Fund
Meet Daniel. Daniel is a US citizen who moved to Auckland and opened a KiwiSaver. He holds two funds: a Growth Fund and a Conservative Fund. In June 2025 he switches entirely out of the Growth Fund into the Conservative Fund — a switch is a disposition of the Growth Fund units for US tax, even though no cash left his KiwiSaver. He files a 2025 Form 8621 for each fund; this example follows only the Growth Fund (the one he sold).
Facts (all converted to USD at the relevant spot rates — see the recordkeeping section):
- Bought the Growth Fund units in June 2020. Held exactly 5 years.
- USD cost basis at purchase: $20,000
- USD proceeds on the June 2025 switch: $32,000
- Total gain on disposition: $12,000
- No QEF or mark-to-market election was ever in place — it is a Section 1291 fund.
- The fund made no actual cash distributions to Daniel during the holding period (KiwiSaver typically reinvests), so the whole $12,000 is a disposition gain treated as an excess distribution.
Step 1 — Part I (information). The de minimis exception is unavailable because Daniel recognised a disposition gain on a Section 1291 fund, so he completes Part I: a description of the fund, the provider as issuer, his units, and the fund's PFIC status.
Step 2 — Part II (elections). Daniel checks nothing. There is no Part II election that makes Section 1291 apply — Section 1291 is the default that applies automatically when no QEF/MTM election is or was in force. (Part II is only where you'd make Election A for QEF or Election C for MTM, neither of which Daniel can use.)
Step 3 — Part V, line 15 (the disposition). Daniel reports the disposition gain of $12,000 as his "excess distribution" for the year on line 15. With no prior distributions to compare against, the entire gain on a Section 1291 fund is treated as an excess distribution.
Step 4 — Part V, line 16 (the §1291 tax and interest math). This is the engine. Under IRC §1291 and the line 16 instructions, the excess distribution is:
- Allocated rateably to each day in his holding period. Daniel held the units for 5 tax years (2020–2025), so the $12,000 is spread roughly evenly across those years. Allocated per full prior year: $12,000 ÷ 5 ≈ $2,400 per year for 2020, 2021, 2022, 2023, and 2024, with the small slice landing in the 2025 (current/sale) year.
- The current-year portion (and any pre-PFIC-period portion) is ordinary income on his 2025 return — no special charge, just added to his other income at his ordinary rate.
- Each prior-year slice is taxed separately at the highest ordinary rate in effect for that year. The §1291 rules do not use Daniel's actual bracket — they use the top individual rate under §1 for each of 2020–2024. That converts what would have been a long-term capital gain into tax at the highest marginal rate, year by year.
- An interest charge is added on each prior-year slice — computed under §6621 using the §6601 rules (the IRS underpayment interest rate), running from the due date of that prior year's return up to the 2025 filing. The longer the slice sat undistributed, the more interest accrues.
The interest-charge math on a 5-year deferral
The interest charge is what makes Section 1291 hurt. It is not a flat penalty — it is compound underpayment interest under §6621, applied to the deferred tax on each prior-year slice, for the time that slice was "deferred." A slice allocated to 2020 accrues interest for about five years; a slice allocated to 2024 accrues for about one. The illustration below uses Daniel's five $2,400 slices, the top individual rate, and an illustrative underpayment rate to show the shape of the calculation — your actual rate must come from the IRS quarterly rate table for each period.
| Slice allocated to | Amount | Tax at top ordinary rate (illustrative 37%) | Approx. years deferred | Interest charge accrues |
|---|---|---|---|---|
| 2025 (current/sale year) | ~$2,400 | Taxed at Daniel's ordinary rate, on 2025 return | 0 | None — current year |
| 2024 | $2,400 | $888 | ~1 | Smallest |
| 2023 | $2,400 | $888 | ~2 | ↑ |
| 2022 | $2,400 | $888 | ~3 | ↑ |
| 2021 | $2,400 | $888 | ~4 | ↑ |
| 2020 | $2,400 | $888 | ~5 | Largest |
What this shows: the four prior-year slices (2020–2024) carry roughly $3,552 of "deferred" tax (4 × $888) before any interest, plus the current-year slice taxed normally. The §6621 interest is then layered on top of each prior-year slice for the years it was deferred. On a five-year hold, that interest can add a meaningful percentage on top of the tax — and because it compounds and uses the top rate, the effective hit on a Section 1291 gain is materially worse than the long-term capital-gains rate you'd have paid on a comparable US fund. The figures above are illustrative of the method; the top individual rate and the §6621 rate for each period are the load-bearing numbers, and you must pull both from the IRS for the exact years involved.
It is tempting to think "no tax until I sell" is good. It is not. Because §1291 spreads the gain back over the holding period and taxes each year at the top rate plus interest, a long hold magnifies the bill rather than shrinking it. The longer a Section 1291 fund grows untaxed, the larger the eventual §1291 charge. This is the core of the FIF/PFIC double-bind for US citizens in NZ.
Recordkeeping you need from your KiwiSaver provider
Form 8621 runs on data your NZ provider was never designed to give you on a US basis. Start gathering this early — chasing it the week before the deadline is how returns go on extension.
| What you need | Why | Will an NZ provider give it? |
|---|---|---|
| Date and USD cost of every purchase / contribution into each fund | Establishes basis and holding period for §1291 allocation | Partly — you usually must reconstruct USD basis yourself from transaction dates + FX rates |
| Date and USD value of every switch, withdrawal or sale | Each is a disposition triggering Part V | Transaction history: yes. USD conversion: no — that's on you |
| Year-end USD market value of each fund | Part I value reporting and the de minimis test | NZD value: yes (annual statement). USD: convert yourself |
| PFIC Annual Information Statement (US-format ordinary earnings + net capital gain) | The only thing that enables a QEF election | Generally no — major KiwiSaver/PIE providers do not produce these |
| Per-period FX rates (NZD→USD) | Every figure on Form 8621 is in USD | No — use a consistent, documented source (e.g. published spot/yearly average rates) |
The single biggest gap is the PFIC Annual Information Statement. If you ask your provider's support team for one, the usual answer is that they do not provide US tax reporting. That answer is what locks most US-citizen KiwiSaver members into Section 1291. Keep the written "no" — it documents why you defaulted to §1291 rather than electing QEF.
Failing to file a required Form 8621 has an outsized consequence: under IRC §6501(c)(8), the statute of limitations can stay open — potentially on your entire return, not just the PFIC items — until the form is filed. A modest KiwiSaver can keep your whole year auditable for far longer than the usual three years. Filing, even late, starts the clock.
- One Form 8621 per fund. A three-fund KiwiSaver normally means three forms — each fund inside the wrapper is its own PFIC.
- Section 1291 is your default because NZ providers don't issue PFIC Annual Information Statements (so no QEF) and managed fund units aren't exchange-traded marketable stock (so no mark-to-market).
- The math lives in Part V (lines 15–16) on the current form — not Part III, despite what older guides say. Check the form's revision date.
- A disposition gain is spread back over the holding period, each prior year taxed at the top ordinary rate, plus a §6621 interest charge that grows with how long you held.
- Verify the live numbers — top individual rate and §6621 underpayment rate per period — from the IRS for the exact years; the worked example shows the method, not your bill.
- Filing matters even when it hurts: a missing 8621 can hold your whole return open under §6501(c)(8).
Frequently asked questions
Do I really file a separate Form 8621 for each KiwiSaver fund?
Yes. Form 8621 is filed per PFIC, and each managed fund inside your KiwiSaver that meets the PFIC tests is a separate PFIC. If you hold three funds, you generally file three forms, each reporting only that fund's value, distributions and dispositions. See the IRS Instructions for Form 8621.
Can I just make a QEF election to avoid the Section 1291 interest charge?
Only if your fund gives you a PFIC Annual Information Statement showing your pro-rata ordinary earnings and net capital gain on a US basis. Major NZ KiwiSaver and PIE providers generally do not produce these, so a valid QEF election usually isn't possible and you default to Section 1291.
What about the mark-to-market election instead?
The §1296 mark-to-market election requires "marketable stock" that is regularly traded on a qualifying regulated exchange. Ordinary KiwiSaver managed-fund units are bought and redeemed at a daily unit price with the provider, not traded on an exchange, so they generally don't qualify. The IRS marketable-stock definition is in the Form 8621 instructions.
Is the Section 1291 calculation in Part III or Part V?
On the current form it is Part V, "Distributions From and Dispositions of Stock of a Section 1291 Fund" (lines 15–16). Older articles say Part III because the IRS later reorganised the form. Always go by the revision date on the actual form you download.
Does switching between KiwiSaver funds trigger Form 8621?
Yes — switching out of a fund is a disposition of that fund's units for US tax, even though no cash left your KiwiSaver. That can create a Section 1291 excess distribution to report in Part V, and it removes the de minimis Part I exception for that year.
What happens if I never filed Form 8621 for my KiwiSaver?
Beyond the tax owed, a missing Form 8621 can keep the statute of limitations open under IRC §6501(c)(8) — potentially on your entire return until you file it. Filing late starts the clock; talk to a cross-border accountant about late-filing and any available relief.
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