01The tax office approaches in stages: an otazune inquiry as administrative guidance, a pre-notice announcing an audit, then the audit itself.02The watershed is the pre-notice: a voluntary amendment before it carries zero underreporting surcharge — or 5% for non-filing. After it: 10 to 30%, and 35 to 40% for concealment.03The data already exists: domestic exchanges file payment records, tax offices hold inquiry powers over dealers, and cross-border automatic exchange keeps widening.
Where the letters come from
Domestic crypto exchanges submit payment records on their customers to the tax authorities, and tax offices can compel transaction histories from dealers by inquiry. Blockchain records do not fade. An otazune rarely arrives by chance: some dataset failed to reconcile with your return. The international frameworks for automatic information exchange are extending to cryptoassets too — the blank space labelled "foreign exchange" shrinks by the year.
The three stages
The otazune. A written inquiry about transactions or filings — legally administrative guidance, not a tax audit. That distinction is everything: because it is not an audit, the voluntary amendment door remains open, and the surcharge waivers with it. The correct reading is neither fear nor relief but arithmetic — recheck every year before the answer deadline, and if gaps exist, design the reply and the correction as one move.
The audit pre-notice. The formal announcement that a field audit will begin — this is the watershed. An amendment filed after it is no longer "voluntary": the underreporting surcharge of 10 percent (15 on larger amounts) and the non-filing surcharge of 15 to 30 percent apply as a rule. From the moment it arrives, every submission is built with a professional.
The audit. Questions, document demands, explanations — all on the record, and anything read as concealment or fabrication brings the heavy surcharge of 35 to 40 percent into view. Representation first, organised copies second, memory-based answers never. An audit is a dialogue, and dialogues are won in preparation.
Spain closes its door with the requerimiento, Italy with the constatazione. Japan's door is the pre-notice — and the step between its two sides, zero versus thirty percent, is the sharpest on this site.
What to do at each stage
- Otazune arrived: recompute every year before answering. If something is missing, pair the reply with an amended return — while the door is open.
- Pre-notice arrived: every filing from here with a tax professional. Record the notice date; fix the scope and deadlines precisely.
- Audit underway: representation present, documents submitted as organised copies, no oral guessing — written facts outrank remembered ones.
- Always: keep the receipt date of every document. The surcharge system turns on dates, and dates are proven on paper.
If a document has arrived, deadlines may be running. This page explains the sequence; it does not answer for you, and reading it creates no professional relationship.