FBAR from Japan: which Japanese accounts actually count (NISA, iDeCo, Yucho, pension)

The short version. If you’re a US person living in Japan and your Japanese accounts add up to more than $10,000 at any point in the year, you file an FBAR (FinCEN Form 114). Ordinary bank accounts, Yucho, brokerage accounts, and your NISA all count. iDeCo almost always counts too — it has a real, ascertainable balance. What generally does not count is government social insurance: Kosei Nenkin (厚生年金) and National Pension (国民年金). The $10,000 line is an aggregate across all accounts, and because it’s measured in dollars, a strong yen can push you over without you touching a thing.

I’m Jin. I’m a Japanese national who spent four years working in US manufacturing and researched the money side of moving between the two countries for my own family. I’m not a licensed tax advisor — this is my own research and reading of the official guidance, not tax advice. For anything with real money on it, confirm against the IRS pages and a professional. This article is only about which accounts to classify as reportable. The bigger “how do I file in my first year” picture lives in my first tax year after leaving the US write-up.

The $10,000 trigger, and why the yen makes it sneaky

The FBAR isn’t a tax. It’s an information report filed separately from your 1040, through the BSA E-Filing system. You file if the combined maximum value of all your foreign financial accounts crosses $10,000 at any single moment during the calendar year — not the year-end balance, the highest point.

Two things trip people up:

• It’s aggregate. A ¥800,000 Yucho account plus a ¥700,000 brokerage account is $10,000+ together, even though neither one alone crosses the line.
• It’s measured in dollars. At roughly ¥150 to the dollar, ¥1,500,000 is $10,000 — a very ordinary savings balance in Japan. The dollar-yen rate has swung between about 130 and 160 in recent years (FRED, USD/JPY). A stronger yen (lower ¥/$ number — closer to 130) raises the dollar value of your yen balances: that same ¥1,500,000 at ¥130 to the dollar is roughly $11,500, over the threshold even though nothing in your account changed. Nothing in your account changed; the exchange rate did.

For conversion you use the US Treasury year-end (December 31) rate, not the IRS annual-average rate you’d use for income. Confirm the exact figure on the Treasury’s reporting-rates page each year before you file.

The Japan classification checklist

Here’s the part people actually search for. This is how the common Japanese accounts sort out.

Account	Japanese	FBAR?	Why
Ordinary / time deposit	普通預金・定期預金	Yes	Deposit account at a foreign bank
Japan Post Bank	ゆうちょ銀行	Yes	Yucho is a licensed bank
Securities / brokerage	特定口座・一般口座	Yes	Investment account with a balance
NISA	NISA口座	Yes	It’s an individual brokerage account; Japan’s tax-free status is irrelevant to US reporting
iDeCo	個人型確定拠出年金	Yes (in practice)	Defined-contribution — you have a real, ascertainable balance
Corporate DC	企業型DC	Yes	Same logic as iDeCo
Kosei Nenkin	厚生年金	No	Government social insurance — no individual account balance
National Pension	国民年金	No	Same — mandatory government program

The dividing line is simple once you see it: does a private financial institution hold a balance with your name on it that you could, in principle, look up? A brokerage does. Yucho does. Your iDeCo custodian (SBI, Rakuten, etc.) does. Kosei Nenkin does not — it’s a pay-in-now, collect-a-pension-later government system with no segregated personal account, which is exactly why it falls under the long-recognized “foreign government social insurance” exception.

When I was preparing my own move, the account that surprised me most was NISA. In Japan we think of NISA as “the tax-free one,” so it’s tempting to assume it gets special treatment abroad too. It doesn’t. The US doesn’t care that Japan made it tax-exempt — to the IRS it’s just an individual brokerage account, and it’s reportable. (Worse, the mutual funds inside a NISA are usually PFICs for US purposes, which is a separate and genuinely nasty problem — I cover that in PFIC and Japanese funds and in NISA and US citizens. Reporting the account on the FBAR does not make the PFIC issue go away.)

The iDeCo gray zone — report it

iDeCo is the one people argue about, so let me be clear about where the argument actually is.

iDeCo is individual-type, defined-contribution. There is a real balance sitting at a private custodian. That makes it fundamentally different from Kosei Nenkin, which has no balance to report. The prevailing practitioner position is straightforward: report iDeCo on the FBAR. The “it’s technically fact-specific” caveat you’ll see refers to edge cases (like someone building a treaty argument), not a routine reason to leave it off.

The trap is that iDeCo locks your money until age 60, so it feels like a pension you can’t touch — and people mentally file it next to Kosei Nenkin. That instinct is wrong. Locked ≠ no balance. If you have to guess, report it. An account wrongly included on an FBAR costs you nothing; an account wrongly left off is where penalties live.

Decision rule:

• Private custodian holds a balance with your name (iDeCo, 企業型DC, brokerage, NISA, bank) → report it.
• Government program, no individual account (厚生年金, 国民年金) → don’t.
• Genuinely unsure → report it. Over-reporting has no penalty; under-reporting does.

FBAR vs. Form 8938 — don’t confuse them

People blur these two together. They’re separate forms with very different thresholds.

	FBAR (FinCEN 114)	Form 8938 (FATCA)
Filed	Separately, via BSA E-Filing	Attached to your Form 1040
Threshold — single, abroad	> $10,000 aggregate, any time	> $200,000 year-end or > $300,000 any time
Threshold — married filing jointly, abroad	Same $10,000	> $400,000 year-end or > $600,000 any time
Govt social insurance	Excluded	Excluded

For most people moving to Japan, the FBAR triggers first, by a wide margin. You can easily clear $10,000 in a Yucho account and a brokerage while being nowhere near the $200,000 that starts the 8938 conversation. Filing one does not satisfy the other, and many accounts appear on both when you’re big enough to owe both.

What ignoring this actually costs

This is why I don’t treat the FBAR as optional paperwork. The civil penalty for a non-willful violation runs into the thousands of dollars per violation — the figure was around $16,500 as of my research (confirm the current FinCEN schedule, as it adjusts each year). Willful violations are far worse — the greater of roughly $165,000 or 50% of the account value. Set against a form that, once you know which accounts to list, takes an evening to file, the math is not close.

And “they’ll never know” isn’t the bet it used to be. Japanese financial institutions report to the US under FATCA agreements. The data is already flowing.

If you’d rather not stare at BSA E-Filing alone your first year, one place to start is Taxes for Expats — a US–Japan expat firm; that link takes $25 off a first filing. (Full disclosure: that’s a referral link. It’s not the only option, and I’m not a tax professional — shop around, and use whoever you trust.) The first tax year piece covers the full filing picture; your US brokerage and 401(k)/IRA decisions are worth sorting before you leave.

FAQ

Is iDeCo FBAR reportable?

In practice, yes. iDeCo is an individual defined-contribution plan with a real balance held at a private custodian, so it has an ascertainable account value — the thing the FBAR is built to capture. The common practitioner position is to report it, and the safe move when uncertain is always to include it.

Does my NISA go on the FBAR or Form 8938?

Potentially both, depending on your totals. NISA is an individual brokerage account, so it’s FBAR-reportable once your aggregate crosses $10,000, and it counts toward Form 8938 if you also clear the much higher 8938 thresholds. Japan’s tax-free status doesn’t change either answer — and remember the funds inside may be PFICs, which is a separate filing issue entirely.

Do I have to report Kosei Nenkin or National Pension?

Generally no. Both are Japanese government social insurance programs with no individual, segregated account balance, so they fall under the recognized foreign-government-social-insurance exception for both the FBAR and Form 8938. The distinction that matters is government program vs. private balance — a company DC plan or iDeCo is the opposite case and does get reported.