(REFERENCE · COOK ISLANDS TRUST · 6 MIN READ)

Tax obligations for a Cook Islands trust

Setting up a Cook Islands trust will not lower what a US person owes in tax. It shifts who legally holds the assets, but not the place where income gets taxed. Here is what has to be filed, on what timeline, and the price of getting it wrong.

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Written and reviewed by Connor SteensJohn Evans

Updated 17 August 2026

Connor Steens

BBUS

Founder & Business Development Director

Sydney, Australia Profile ↗ LinkedIn ↗

John Evans

Forbes Business Council

Founder & Chief Executive Officer

Rarotonga, Cook Islands Profile ↗ LinkedIn ↗

Asia PacificCook Islands

The fundamental point

For US tax purposes, a Cook Islands trust is treated as a foreign grantor trust. That means the settlor declares the trust's income on their personal US return as though, for income tax, the trust simply did not exist. While the arrangement shifts legal title to the assets, it leaves untouched where that income is taxed, the amount of tax due, and the disclosures owed to the IRS. Should a US person establish such a trust and then neglect the mandatory filings, the resulting penalties can far exceed the tax that was owed in the first place.

Far from a technicality, this is the core reality of how a Cook Islands trust is taxed, and it is something anyone weighing the structure needs to grasp before establishing anything. The creditor protection on offer is genuine and worthwhile; it simply has nothing to do with cutting taxes. Treating it as a tax-cutting device is not only wrong but also breeds exactly the sort of compliance breakdown that triggers the harshest IRS penalties.

Annual filings

When a US person is the settlor of a foreign grantor trust, two forms have to go to the IRS each year, whether or not distributions were paid, transactions took place, or the trust did anything at all during that year. Form 3520 captures dealings with the foreign trust, including its initial creation and funding, any later contributions, and distributions the settlor receives. Form 3520-A serves as the trust's yearly information return, detailing its assets, income, and distributions across the year. Each falls due on the personal return's due date and shares the same extension rules.

The consequences are harsh. Missing Form 3520 triggers a penalty equal to the greater of $10,000 or 35 percent of the gross reportable amount, and Form 3520-A brings comparable penalties. These bear no proportion to how small the mistake was. On a sizeable trust, an overlooked filing produces a penalty that far outstrips what correct filing would have cost. A CPA who routinely prepares these returns for Cook Islands trust clients ought to take care of both, year after year.

Automatic reporting

The Cook Islands is a participant in the OECD Common Reporting Standard. Banks that hold balances for Cook Islands trust accounts automatically pass account details to the FSC, which in turn shares them with the tax authorities where account holders reside. Whether or not a US settlor chooses to file, information on their trust account still reaches the IRS via CRS. A trust left off the Forms yet visible through CRS becomes one the IRS knows about from two sources that do not match.

Obligations under FBAR and FATCA apply on their own footing. Any US person holding a financial interest in, or signature authority over, a foreign financial account that tops $10,000 in value at any moment in the year has to file an FBAR. FATCA, meanwhile, calls for reporting specified foreign financial assets that exceed set thresholds on Form 8938.

In this section

Form 3520 — the yearly return covering dealings with foreign trusts
Form 3520-A — the trust's yearly information return
FBAR and FATCA — reporting of foreign accounts and assets
CRS reporting — automatic exchange and its implications

General guidance only. Tax rules shift and personal situations differ. Verify every obligation with a CPA who has direct experience filing for Cook Islands trusts, both before you settle a trust and every year afterward.

Speak to a specialistLooking for a CPA versed in Cook Islands trusts?We can put you in touch with a specialist who handles these filings on a regular basis.Book a consultation Cook Islands Trust formation starting at $10,000, first-year trustee costs included.

(Review & sourcing)

Written by

Connor Steens

BBus, business development

Reviewed by

John Evans

20+ years, offshore structuring

Last updated

17 August 2026

General information

Sourced from

IRS publications and practitioner guidance

Verify the current requirements with a qualified CPA

01IRS Form 3520 — yearly return for dealings with foreign trusts.

02IRS Form 3520-A — yearly information return covering foreign trusts.

03FinCEN FBAR guidance — reporting on foreign bank and financial accounts.

04IRS FATCA guidance — Foreign Account Tax Compliance Act.

(COMMON QUESTIONS)

Common questions covering the tax responsibilities tied to a Cook Islands trust

No. Under US tax law a Cook Islands trust counts as a foreign grantor trust, so the settlor declares the trust's income on their personal return as though the trust were not there. For US income tax, where the trustee sits makes no difference.

Forms 3520 and 3520-A, both tied to the personal tax return's schedule. Form 3520 covers dealings with the trust, while Form 3520-A is the trust's yearly information return. Both have to be submitted even in a year with no distributions or transactions.

For Form 3520, the greater of $10,000 or 35 percent of the gross reportable amount, with Form 3520-A carrying comparable penalties. They land on each missed filing and bear no proportion to how small the error was.

Most likely yes, by way of CRS automatic exchange. The Cook Islands shares financial account information with the IRS automatically. When a trust that was never voluntarily disclosed surfaces through CRS, the mismatch is something the IRS will pick up on.

Report of Foreign Bank and Financial Accounts. It is required whenever a US person holds a financial interest in, or signature authority over, a foreign account exceeding $10,000 in value at any point in the calendar year. It goes to FinCEN rather than the IRS.

The Cook Islands levies no income tax on the income of international trusts. Tax responsibilities fall on the settlor and beneficiaries within their own countries, not on the trust in the Cook Islands.

A CPA who regularly handles these forms for Cook Islands trust clients. Given how severe the penalty regime is for mistakes, having someone learn the ropes on your return is not a sensible choice.

What the structure delivers is protection from creditors, not tax breaks. Properly run, a Cook Islands trust gives a US person no tax edge over simply owning the same assets outright. Anyone who claims otherwise is describing a benefit the statute does not grant.