Japan has no special disclosure programme and no once-only pardon. What it has is a single principle built into the General Tax Act: correct voluntarily before the audit pre-notice, and the surcharges vanish or shrink dramatically. Underreporting: zero surcharge. A return never filed at all: 5 percent — against 15 to 30 after the pre-notice, and 35 to 40 for concealment (more for repeat offenders). Principal tax and late-payment interest always remain. What disappears is the penalty, never the tax.
Two forms, one principle
You filed but understated — an amended return. You never filed — a late return. Crypto cases usually involve both: years where swaps and payments were not counted as sales, years where the ¥200,000 rule was misread and the inhabitant tax dropped with it, years where only the foreign-exchange leg went missing. Either form follows the same principle: filed before the pre-notice, light; after, heavy. And the recomputation rebuilds each year under the total-average method — stacking exchange CSVs is not the NTA's calculation sheet.
Vienna forgives sequence, Bern forgives once, Berlin demands the decade, Madrid bills by tariff, Paris grades by date, Rome trims its discount monthly. Tokyo is the tersest of all: "Come before the notice, and there is no surcharge." The eleventh jurisdiction — and the shortest sentence in the matrix.
Time as the only variable
This system has one moving part: the day the pre-notice lands. Principal tax is fixed; late interest accrues daily regardless — only the surcharge moves, and it moves on a date. When an otazune arrives, the door is still open. With payment records, dealer inquiries and widening international exchange stacking the data year by year, the expected value of "they won't find it" deteriorates annually. Replace the bet with subtraction: total cost of amending today versus after the notice — the decision stops being emotional and becomes arithmetic.
The sequence
- Recompute before deciding. Every open year, every exchange, yen conversions, total-average — the real number surprises, in both directions.
- File complete, year by year, at once. Amended and late returns for all affected years together — partial fixes only spotlight the remaining inconsistencies.
- Pay with the filing. Principal and late interest attached — the correction completes on payment.
- Do not forget inhabitant tax. An income-tax correction ripples to the municipality; the correction closes only when both do.
- If the pre-notice already arrived, change the design. The zero door is shut — from here you manage surcharge bands and audit response, with a tax professional.
Surcharges, interest and deadlines turn on facts and dates this page does not know. It frames the decision; it does not make it, and reading it creates no professional relationship.