Japanese iDeCo and NISA: US Tax and Reporting Implications

Japan's iDeCo (Individual Defined Contribution Pension) and NISA (Nippon Individual Savings Account) are popular tax-advantaged accounts in Japan, but neither receives recognition as tax-advantaged by the IRS. iDeCo is a self-directed personal pension — contributions are deductible in Japan and earnings accumulate tax-free, but for US purposes, the account is treated as a foreign pension plan and contributions may not be deductible on the US return, with earnings potentially taxable annually. NISA is Japan's equivalent of a Stocks and Shares ISA — a tax-free investment account — but like the UK ISA, the IRS does not honor its Japanese tax-free status, and gains and income inside the NISA are fully taxable on the US return. Funds held inside iDeCo or NISA that are Japanese mutual funds or ETFs are likely PFICs, adding the PFIC tax layer on top of ordinary income taxation. Both accounts must be reported on FBAR and potentially Form 8938.