Why Crypto Is Miscellaneous Income in Japan, and the Cost

Almost every difficult feature of Japanese crypto tax follows from one classification decision. Crypto profit is not a capital gain in Japan. It is miscellaneous income, and once you understand what that category does, the high rate, the missing loss relief and the absence of a separate flat rate all stop being surprises.

The classification

FAQ section 2-2 states the rule: profit arising from crypto transactions is subject to income tax and is in principle classified as miscellaneous income, in the residual sub category. The reasoning given is that gains and losses on crypto are recognised through a relative relationship with domestic or foreign currency.

The same section sets out the exception. Where revenue from crypto transactions for the year exceeds 3,000,000 yen, the classification depends on records: with books and documents retained for the crypto activity, it is in principle business income; without them, it is miscellaneous income in the business related sub category. A note added in the December 2025 revision qualifies this: even where books are retained, if the activity lacks a profit making character, whether it is business income is judged individually. Separately, where crypto activity is incidental to something that generates business income, for example a business holding crypto as a business asset and using it to settle purchases of inventory, it is classified as business income.

What the classification costs you

Aggregate taxation at your marginal rate. Miscellaneous income is added to your other income and taxed at progressive national rates of 5% to 45% plus a flat 10% resident tax, so the effective ceiling is around 55%. Crypto is not subject to the separate flat taxation that applies to listed share gains.

No loss offsetting. FAQ section 2-11 states that losses arising in the computation of miscellaneous income cannot be offset against salary or other income, because the Income Tax Act limits offsetting to real estate, business, forestry and capital gains income. A year in which your crypto position halves does not reduce the tax on your salary.

A gain lands on top of your stack. Because the income aggregates, the relevant rate is the one at the top of your total income, not an average. This is why people who model their crypto gain at last year's effective rate under-reserve.

What is deductible

FAQ section 2-3 gives the necessary expenses for income from selling crypto: the cost of the crypto disposed of, and the fees paid on the sale. Beyond that, expenditure such as internet or mobile line charges and the cost of a computer can be included only to the extent it is recognised as directly required for the crypto sale. The section adds two cautions: line charges are usually paid as one bundled amount, so they can be included only where the crypto related portion is clearly separable; and an asset with a useful life of a year or more above a certain amount must be depreciated over its useful life rather than expensed in one year.

Where the income is business income or business related miscellaneous income, selling and general administrative expenses of the activity may also be included.

The proposed flat rate

A move from miscellaneous income to separate flat taxation, treating crypto more like listed shares, has been proposed. It is not enacted. Until it is, the miscellaneous income framework above is what applies, and you should not plan on the basis that a flat rate is already in force. Check the current position before making a decision that depends on it.

What this means in practice

• Reserve tax at your marginal rate, not your average one.
• Realise offsetting losses within the same calendar year if you are going to realise them at all, since they cannot travel to another year or another income category.
• Keep records good enough that your deductible costs and your acquisition costs are actually claimed, since both directly reduce the number the rate is applied to.
• If your crypto revenue for the year is large, understand the records based classification split in section 2-2 before assuming which category you are in.

Our Japan crypto tax guide covers the rates and rules, and the crypto tax calculator computes the income figure the rate is applied to.

General information, not tax advice. Verify your classification and current rates with the National Tax Agency or a qualified tax professional.