How Much Tax Do You Pay on FX Profits in Japan? A Salary Worker's Guide

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If you are a salaried worker in Japan dabbling in foreign exchange trading, one question will inevitably arise when the numbers start moving in your favor: how much of that profit actually belongs to you, and how much goes to the Japanese tax authority? Understanding FX tax in Japan is not complicated once you know the rules, but getting it wrong can lead to unexpected bills, penalties, or missed deductions. This guide walks you through everything you need to know, from the headline tax rate to the filing process.

FX Tax Rate in Japan — The 20.315% Rule

The single most important number to memorize is 20.315%. That is the flat tax rate applied to realized FX profits in Japan, regardless of how large your gain is. Unlike employment income, which is subject to progressive rates that climb as high as 45% at the national level, FX profits benefit from a separate, fixed “申告分離課税” (separate declaration tax) system.

The 20.315% is not one tax — it is a combination of three:

National income tax at 15% is the core levy collected by the national government on gains from financial instruments classified under “先物取引に係る雑所得” (miscellaneous income related to futures transactions). FX trades executed through Japanese brokers are legally treated as futures contracts under the Financial Instruments and Exchange Act, which is why this favorable flat rate applies rather than the ordinary progressive rate on miscellaneous income.

Reconstruction special income tax at 0.315% is a surcharge introduced after the 2011 Great East Japan Earthquake to fund reconstruction. It is calculated as 2.1% of the national income tax amount (2.1% × 15% = 0.315%). This surcharge applies to all income taxes and currently runs through the 2037 tax year.

Residence tax at 5% is collected by your municipality rather than the national government. It is based on your previous year’s income and is typically withheld from your monthly salary starting in June after you file your return. The 5% rate on FX gains is uniform nationwide.

One practical implication of this structure: if you are trying to estimate your after-tax FX profit quickly, simply multiply your gain by 0.79685. That is how much you keep.

When Do Salaried Workers Need to File?

Japan has a specific rule that gives salary workers a partial reprieve from filing paperwork, but it comes with an important asterisk.

The ¥200,000 threshold: If your total “other income” — which includes FX profits, side job revenue, rental income, and similar items — is ¥200,000 or less in a calendar year, you are not required to file a national income tax return (確定申告, kakuteishinkoku). This exemption applies only to people whose salary income comes from a single employer that withholds year-end tax adjustments (年末調整).

The asterisk — residence tax still applies: Even if you fall under the ¥200,000 threshold and skip the national tax return, you are still legally required to report that income to your municipality for residence tax purposes. You do this by filing a “住民税申告” (residence tax declaration) directly with your local city or ward office by March 15. Many people overlook this step and later receive an unexpected bill or notice from their municipality.

When you must file regardless:

• Your FX profit exceeds ¥200,000 in the calendar year
• You have income from multiple employers
• You have other reasons requiring a kakuteishinkoku (medical expense deductions, home loan deductions, etc.)
• You want to carry forward FX losses to future years (explained below)

The filing deadline for the kakuteishinkoku is March 15 of the following year, covering income earned in the previous calendar year (January 1 to December 31).

How to Calculate Your FX Tax

The calculation itself is straightforward. Your taxable FX income is:

Realized FX profit − Deductible losses and costs = Net taxable income

Deductible costs include trading commissions paid to your broker and, in some cases, costs directly attributable to your trading activities (such as software subscriptions used exclusively for FX analysis). Unrealized gains on open positions are not taxable — only profits locked in by closing a trade count.

Once you have your net taxable income, apply 20.315%.

Example 1: ¥300,000 profit

At this level you are also above the ¥200,000 threshold, so a kakuteishinkoku is required.

Example 2: ¥500,000 profit

Notice that even though your gross profit doubled compared to Example 1, the effective percentage going to tax remains exactly 20.315%. This is the advantage of the flat-rate separate taxation system.

Example 3: ¥1,000,000 profit

For a salaried worker whose employment income is already taxed at a combined marginal rate of 30–40% or higher, the 20.315% rate on FX gains is significantly more favorable. A trader in the 33% national income tax bracket, for example, saves roughly 13 percentage points by having gains taxed under the separate declaration system rather than as ordinary miscellaneous income.

Use our FX Profit Calculator for instant results without doing the math manually.

What About FX Losses?

Losses are not simply written off and forgotten. Japan’s tax code gives FX traders a meaningful tool: the 3-year loss carryforward (損失の繰越控除).

If your FX trading results in a net loss in a given year, you can carry that loss forward and offset it against FX profits in the following three years. This can substantially reduce your tax bill in profitable years that follow a losing streak.

How it works in practice:

• Year 1: Net FX loss of ¥400,000 → file a return, record the loss
• Year 2: Net FX profit of ¥250,000 → offset against ¥250,000 of the carryforward loss, taxable income = ¥0, remaining carryforward = ¥150,000
• Year 3: Net FX profit of ¥300,000 → offset against remaining ¥150,000, taxable income = ¥150,000, tax = ¥30,472

Without the carryforward, Year 3 tax would have been ¥60,945 on the full ¥300,000. The carryforward saved approximately ¥30,473.

Critical requirement: you must file every year. The carryforward is only available if you file a kakuteishinkoku in the year the loss occurred and in every subsequent year you want to maintain the carryforward. If you skip a year’s filing — even a year in which you had no FX activity — the carryforward is extinguished. This is one of the most costly mistakes FX traders make.

The loss carryforward applies specifically to losses classified under the futures-related miscellaneous income category. It cannot be used to offset ordinary salary income or other categories of income.

FX vs Stock Trading Tax — Similar but Not Interchangeable

Both FX profits and listed stock trading profits are taxed at the same headline rate of 20.315%, which can make them seem equivalent from a tax perspective. They share the rate but not the category, and that distinction matters.

FX profits are classified as “先物取引に係る雑所得” — miscellaneous income related to futures transactions.

Listed stock profits (from shares, ETFs, investment trusts) are classified as “株式等に係る譲渡所得” — transfer income related to shares and similar instruments.

Because they fall into different categories, FX losses cannot be offset against stock gains, and stock losses cannot be offset against FX gains. Each is ring-fenced within its own category.

One frequently misunderstood point: stock investors can elect to offset stock trading losses against dividend income within the same tax category. FX traders have no equivalent option — FX losses can only be offset against future FX gains.

Another important distinction is NISA (少額投資非課税制度), Japan’s tax-exempt investment account. NISA applies exclusively to stocks, investment trusts, and ETFs. FX margin trading is explicitly excluded, so there is no tax shelter equivalent available for FX profits.

How to File Your FX Tax Return

For most salaried workers, filing a kakuteishinkoku for FX income is a one-time learning curve that becomes routine in subsequent years. Here is the process:

Step 1: Gather your documents

Your FX broker is required to issue an annual trading statement (年間取引報告書) by late January for the previous year’s activity. This document summarizes total realized profit and loss, commissions paid, and other relevant figures. Download it from your broker’s online platform.

Step 2: Choose your filing method

The National Tax Agency (NTA) offers e-Tax, its online filing system, which is the most efficient option. You can access it at the NTA’s website using a My Number Card and a compatible card reader or smartphone. e-Tax pre-fills some fields and reduces manual errors.

Alternatively, you can download paper forms and mail them, or visit a tax office in person. However, e-Tax is strongly recommended for its speed and the immediate confirmation it provides.

Step 3: Complete the correct forms

FX income is reported on the kakuteishinkoku B form (確定申告書B). Within that return, you need to attach:

• Schedule 3 (第三表): “Separate taxation income declaration table” — this is where you declare the FX profit amount and calculate the 20.315% tax
• Attachment form for futures-related miscellaneous income (先物取引に係る雑所得用の付表): This attachment provides the detailed breakdown of trades and is required when claiming a loss carryforward

If you are carrying forward a loss from a prior year, you will also reference the prior year’s filed return to confirm the amount.

Step 4: Report residence tax preference

On the kakuteishinkoku, there is a section where you can elect how your residence tax on separately-taxed income is assessed. In most cases, the default “普通徴収” (ordinary collection) option keeps your FX income details separate from the notice sent to your employer, preserving privacy about your trading activity.

Step 5: Pay any tax owed

Tax due can be paid via e-Tax bank transfer, convenience store payment slip, credit card (through the NTA payment portal), or at a bank. The deadline for both filing and payment is March 15.

freee guides you through Japanese tax filing step by step, including FX income reporting, in a way that makes the process manageable even if your Japanese is limited. The software asks guided questions and automatically routes your answers to the correct form fields.

Common Mistakes to Avoid

1. Forgetting that residence tax still applies below ¥200,000

The ¥200,000 exemption only waives the requirement to file a national income tax return. Your municipality still expects a residence tax declaration. Skipping this is a compliance error and can result in a notice or, in rare cases, a penalty.

2. Not filing loss years

As explained above, the 3-year loss carryforward is voided if you fail to file in the loss year or any subsequent year. A loss that feels insignificant — say, ¥50,000 — could offset a sizeable future gain if preserved through consistent filing. The cost of filing is small; the cost of losing the carryforward can be substantial.

3. Missing the annual trading statement

Some brokers issue statements only through their platform rather than mailing them. If you changed brokers during the year, collect statements from all brokers you used. Every realized trade is taxable regardless of which platform executed it.

4. Treating swap income as non-taxable

Swap interest (スワップポイント) earned on carry trade positions is also taxable as FX miscellaneous income. It appears separately on your annual trading statement but must be included in your total.

5. Mixing personal and trading expenses

A portion of expenses like internet bills or trading software subscriptions may be deductible if they are genuinely and proportionally used for trading. However, claiming excessive or personal expenses as deductions invites scrutiny. Keep clean records with receipts and document the business purpose.

6. Assuming your employer handles it

Year-end tax adjustment (年末調整) conducted by your employer covers only your employment income. It does not touch FX profits under any circumstances. You are solely responsible for declaring and paying tax on FX gains.

7. Confusing the calendar year with fiscal year

Japan’s personal income tax year runs January 1 to December 31, not April to March (which is the government fiscal year). All trades closed between January 1 and December 31 of a given year are reported together in the kakuteishinkoku filed the following January–March.

Conclusion

FX trading as a salaried worker in Japan carries a clear and manageable tax obligation. The 20.315% flat rate is favorable compared to the progressive income tax rates applied to employment income, but it requires active compliance: filing an annual return, reporting to your municipality even in low-profit years, and rigorously maintaining loss carryforward records.

The key numbers to keep in mind:

• 20.315% on all net realized FX profits
• ¥200,000 threshold below which the national return is not required — but the residence tax declaration still is
• 3 years of loss carryforward, contingent on filing every year
• March 15 annual deadline for filing and payment

Getting these basics right puts you in full compliance and positions you to take full advantage of the deductions and carryforwards available under Japanese tax law.

Check your take-home pay after FX taxes to understand the full picture of what you earn and keep each year.

Related Articles

• NISA vs FX in Japan: Which Is Better for Growing Your Money?
• FX Loss Carryforward in Japan: How to File
• Best FX Brokers in Japan (English Guide)
• FX Spread Comparison Japan 2026
• Kakuteishinkoku FX Income Guide

Related Tools

Calculate forex profits → Forex Profit Calculator Estimate your tax bracket → Tax Bracket Calculator Calculate your take-home pay → Salary Calculator

This article is for informational purposes only and does not constitute tax advice. Tax rules can change. Consult a licensed tax accountant (税理士) for advice specific to your situation.