Your Dual-Citizen Child's US Taxes

It surprises almost every cross-border family: your child is a US taxpayer too, from the day they’re born a citizen. The reassuring news is that most young children owe nothing and don’t even have to file. The catch is everything around the tax bill — a reporting form in the child’s own name, a couple of investment traps that turn a kind gift into an expensive mess, and a credit worth real money if you claim it the right way. This is the Family-meets-Money guide; for how the child becomes a US citizen in the first place, see Having a Baby in Japan and US–Japan Dual Citizenship for Your Children.

Yes — a US taxpayer from birth

US tax follows the citizen, at any age: a US-citizen child owes US tax on their worldwide income under the same rules as an adult, with no minimum age. But “taxpayer” isn’t the same as “has to file” — whether a child must actually file a return depends on how much, and what kind of, income they have.

When a child actually has to file

For a dependent child (2025 figures), a US return is required if any of these is true:

• Unearned income (interest, dividends, capital gains) over $1,350.
• Earned income (a job) over $15,750 — the standard deduction.
• Net self-employment earnings of $400 or more.

A child with no income — the typical case — files nothing. But two situations catch families with savings set aside for a kid:

• The “kiddie tax” (Form 8615). A child’s unearned income above $2,700 (2025) is taxed at your marginal rate, not the child’s. So a custodial brokerage account or a fund a grandparent set up can be taxed as if it were the parents’ top-bracket income.
• Folding it into your return (Form 8814). If a child’s only income is interest and dividends under $13,500, you can elect to report it on your own return instead of filing a separate one for the child — though a separate child return is often cleaner.

The child’s own FBAR — the trap nobody expects

This is the one that blindsides people. The FBAR rules apply to a US person of any age — so an account held in your child’s name is the child’s to report, no matter who opened it or whose money is in it. The classic trigger is exactly that: a ゆうちょyūcho account a grandparent opened in the baby’s name (or a gift of savings, or a custodial account). Once the child’s foreign accounts together top $10,000 at any point in the year, an FBAR is due in the child’s name — there is no minor exemption. The child is the filer, but since a toddler can’t, a parent or guardian files and signs it for them (marked “Parent/Guardian filing for child”).

(The separate FATCA form, Form 8938, can also apply, but its thresholds for people living abroad are far higher — a child almost never reaches them.)

The investment traps: PFIC and 学資保険

This is where well-meant generosity gets expensive. Two things to head off before anyone acts:

• PFICs. If a relative buys the US-citizen child Japanese mutual funds (投資信託tōshi shintaku) — including the funds inside a Junior NISA — those are PFICs under US law, which drags the child into one of the most punitive corners of the US tax code, with a separate Form 8621 for each fund, every year. The NISA tax break is Japanese and gives the child no US protection at all. (Individual shares and plain cash aren’t PFICs — it’s pooled funds that are caught. See Investing from Japan as a US Person.)
• 学資保険gakushi hoken (education endowment insurance). One of the most common gifts for a child in Japan — and a genuine US headache. As a foreign insurance-and-savings product it can trigger the 1% US federal excise tax on the premiums (Form 720, almost universally missed), annual US tax on its internal growth, and — depending on how the particular policy is built — possible PFIC or foreign-trust reporting on top. There’s no clean IRS guidance on it, so for a US-citizen child it’s often a poor fit. Have any specific policy reviewed before buying it.

The upside: the Child Tax Credit — and the FEIE catch

It’s not all traps. A qualifying US-citizen child is worth a Child Tax Credit of up to $2,200 (2025), and $1,700 of that is refundable — meaning you can receive it as a payment even if you owe no US tax. Two requirements: the child needs an SSN (not an ITIN) by the return’s due date, and — new for 2025 — the parent claiming it needs a valid SSN too. (Getting the child’s SSN is covered in Having a Baby in Japan.)

Here’s the planning point that’s worth real money: claiming the Foreign Earned Income Exclusion (Form 2555) forfeits the refundable part entirely — “if you file Form 2555, you cannot claim the additional child tax credit.” The Foreign Tax Credit keeps it, because it leaves your earned income on the return (the refundable credit is figured from that income). For a Japan-based family with SSN-holding kids, the FEIE-vs-Foreign-Tax-Credit choice can therefore be worth up to $1,700 per child — frequently the deciding factor for using the Foreign Tax Credit instead of the exclusion. Run it both ways.

Why this matters even when nothing’s owed

Most years, a dual-citizen child owes the US nothing. So why bother? Because compliance now buys options later. Keeping the child’s (simple) filings current is what preserves the dual-citizen-at-birth exit-tax exception if they ever decide, as an adult, to give up US citizenship — that exception only works for someone who can certify five clean years of US tax compliance (see US–Japan Dual Citizenship for Your Children). A small habit kept up through childhood keeps the expensive door from slamming shut.

The short version

• A US-citizen child owes US tax on worldwide income from birth, but most young kids don’t have to file (thresholds: unearned over $1,350, earned over $15,750, self-employment $400+).
• Investment income can trip the kiddie tax (unearned over $2,700 taxed at the parent’s rate).
• The child’s own FBAR is the surprise: an account in the child’s name (the ゆうちょyūcho one grandma opened — whoever funded it) is the child’s to report, and once foreign accounts top $10,000 a filing is due in the child’s name (a parent files it).
• Investment traps: gifted Japanese funds are PFICs (NISA gives no US cover), and 学資保険gakushi hoken carries overlapping US insurance/excise/PFIC/trust exposures — review before buying.
• Child Tax Credit: up to $2,200/child ($1,700 refundable) with an SSN — but the FEIE forfeits the refundable part; the Foreign Tax Credit keeps it.
• Keep them compliant — it preserves the exit-tax exception if they ever renounce later.

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This guide is general information, not tax advice. Children’s US tax, the kiddie tax, PFIC and foreign-insurance treatment, and the credit rules are intricate and change yearly — verify against the sources below and work with a professional experienced in US tax for Americans in Japan, especially before buying any Japanese investment or insurance product for a US-citizen child.