The progression, in practice
Gains from selling, swapping, spending or receiving cryptoassets fall, as a rule, into miscellaneous income, aggregated with salary and other income under comprehensive taxation. Income tax runs 5 to 45 percent, plus 10 percent inhabitant tax and a 0.945 percent reconstruction surtax — a top marginal rate of 55.945 percent. Equities and investment funds sit in a different world at a flat 20.315. The key word is "aggregated": crypto gains are taxed on top of your salary, so the same gain costs more the more you earn.
Taxed without touching yen
The taxable event is not just a sale into yen. Swap BTC for ETH and the BTC gain crystallises that instant. Buy goods with crypto — the same. Staking rewards, lending interest and airdrops become income at market value on the day received, and that value becomes the cost basis for the next disposal. Cost computation defaults to the total-average method; a filed notification switches you to moving average, and the chosen method locks for three years in principle. Re-deriving a year of trades in yen, across exchanges, is the heaviest bookkeeping in this schedule.
The ¥200,000 rule: half an exemption
Salaried employees whose total miscellaneous income stays at or under ¥200,000 for the year need not file an income-tax return. But the exemption covers income tax only — inhabitant-tax obligations remain regardless of the amount. And in any year you file a return anyway — medical deductions, a first-year mortgage credit — the sub-¥200,000 crypto income must be included. "Under 200k means nothing to do" is the most widely believed misreading in this system.
Germany rewards a year of waiting with zero; France waits for you to touch euros. Japan taxes every swap and lets losses die on 31 December — a design where patience earns nothing and motion always bills.
Losses: the harshest line
Crypto losses offset only within miscellaneous income. Not salary, not equity gains. And there is no carryforward — a loss still standing on 31 December simply vanishes for tax purposes. Carry unrealised losses across New Year, or realise them against same-year gains: that decision exists only in December and is gone by January. The regime expected in 2028 brings a three-year carryforward — but only once it takes effect.
What to do
- Log every transaction in yen. Timestamps, quantities, yen values, fees — in a shape that flows into the NTA's total-average calculation sheets.
- Count swaps and payments as sales. Transactions where no yen moves are the largest source of missed income.
- Design the year's landing in December. With no carryforward, a loss can only ever meet a same-year gain.
- Remember inhabitant tax below ¥200,000. The exemption is income-tax only — the municipal filing is a separate duty.
This page explains computational rules. It is not advice on your transactions, and reading it creates no professional relationship.