Japan Offshore Forex Tax Calculator: Estimate Your Tax

Updated 2 November 2026 · Written by Broker Atlas Guides Desk · Data checked by Broker Atlas Data Desk

Short answer

For residents of Japan, profit from an offshore (unregistered) forex broker is generally miscellaneous income taxed with your other income at progressive national rates of 5–45%, plus a 2.1% reconstruction surtax and about 10% resident tax. This calculator estimates how much extra tax your forex profit adds. Example: with ¥3,000,000 of other taxable income, ¥1,000,000 of offshore forex profit adds about ¥273,570.

Who this calculator is for

This tool estimates Japanese tax on profit from an offshore forex broker, for people who are tax residents of Japan, including foreign nationals living there. It applies the National Tax Agency’s (NTA) income tax rate table and the standard resident tax rate. If you live elsewhere, your own country’s rules apply instead: see our forex tax guide.

How to use it

Offshore forex profit for the year (yen, after expenses). Add up the realised profit and loss on all positions closed between 1 January and 31 December, plus swap, across all your offshore brokers, convert it to yen, and subtract allowable expenses. What counts as an expense is explained in deductible trading expenses in Japan.
Other taxable income (yen, after deductions). Your taxable income from everything else, such as salary, after income deductions. For employees, take “employment income after the employment income deduction” from your withholding certificate and subtract “total income deductions”.

The result is the increase in tax caused by adding your forex profit, split into national income tax (including the reconstruction surtax) and resident tax.

The formula

The calculator uses the NTA’s quick-calculation table for income tax (Tax Answer No. 2260):

Taxable income	Rate	Deduction
¥1,000 – ¥1,949,000	5%	¥0
¥1,950,000 – ¥3,299,000	10%	¥97,500
¥3,300,000 – ¥6,949,000	20%	¥427,500
¥6,950,000 – ¥8,999,000	23%	¥636,000
¥9,000,000 – ¥17,999,000	33%	¥1,536,000
¥18,000,000 – ¥39,999,000	40%	¥2,796,000
¥40,000,000 and over	45%	¥4,796,000

Extra income tax = tax on (other income + forex profit) − tax on (other income). Taxable income is rounded down to the nearest ¥1,000 before the table is applied.
Reconstruction surtax: the extra income tax is multiplied by 1.021 (No. 2260).
Resident tax = forex profit × 10%, the standard income-based rate set out by the Ministry of Internal Affairs and Communications.

The basis for treating offshore forex profit as miscellaneous income taxed with your other income is NTA Tax Answer No. 1521.

Worked examples

Example 1: other taxable income ¥3,000,000, forex profit ¥1,000,000

Income tax on ¥4,000,000 = ¥4,000,000 × 20% − ¥427,500 = ¥372,500
Income tax on ¥3,000,000 = ¥3,000,000 × 10% − ¥97,500 = ¥202,500
Extra income tax: ¥170,000 × 1.021 = ¥173,570
Resident tax: ¥1,000,000 × 10% = ¥100,000
Total: ¥273,570

Example 2: other taxable income ¥6,000,000, forex profit ¥500,000

Income tax on ¥6,500,000 = ¥872,500; on ¥6,000,000 = ¥772,500
Extra income tax: ¥100,000 × 1.021 = ¥102,100
Resident tax: ¥500,000 × 10% = ¥50,000
Total: ¥152,100

In Example 1, the first ¥300,000 of forex profit falls in the 10% band and the remaining ¥700,000 in the 20% band. That’s the key feature of taxation together with other income: the more you already earn, the higher the rate on your forex profit. Domestic registered brokers’ flat 20% (15% + 5%) can therefore be cheaper for higher earners, which is one of the trade-offs covered in domestic vs offshore brokers.

What the result means, and its limits

It’s an estimate. It ignores deductions that change as your income rises (such as the spouse deduction), resident tax adjustments and the flat per-capita levy, hometown tax donations (furusato nōzei) and other factors.
Future changes. The NTA explains that a defence special income tax will be introduced from the 2027 tax year, while the combined rate with the reconstruction surtax stays the same (No. 2260).
Filing. Employees generally need to file a tax return if non-salary income exceeds ¥200,000 a year (No. 1900). See the ¥200,000 rule explained, how losses are treated and why brokers ask for your My Number.
Not advice. We explain the general rules only. Confirm your actual liability with your local tax office or a licensed tax accountant (zeirishi).

Related tools: the profit calculator works out the profit on a single trade, and the compound calculator projects a balance over time.

Frequently asked questions

Is offshore forex taxed differently from forex with a Japanese broker?

Yes. According to the National Tax Agency (Tax Answer No. 1521), over-the-counter FX with a registered Japanese firm is taxed separately at 15% income tax plus 5% resident tax. Other FX, including offshore brokers, is generally miscellaneous income added to your other income.

What should I enter as 'other taxable income'?

Your taxable income from everything except offshore forex, after deductions such as the basic deduction and social insurance. For employees, the withholding certificate (gensen chōshūhyō) shows employment income after the employment deduction and the total of income deductions; subtract the second from the first.

If my profit is ¥200,000 or less, do I pay no tax?

Not necessarily. An employee whose non-salary income is ¥200,000 or less may not need to file a national income tax return (NTA No. 1900), but the income is still subject to resident tax, which must be declared to your municipality.

Does this calculator work for a loss?

No, it only calculates a profit. Offshore forex losses generally can't be offset against salary or other income outside miscellaneous income, and can't be carried forward (NTA No. 1521).

I'm not a resident of Japan. Does this apply to me?

No. These rules apply to Japanese tax residents. Non-residents are taxed under different rules, and your country of residence will have its own. Our general tax guide covers the principles.