Basis Passport: your basis is yours.

Every crypto-tax tool locks your history in. We publish ours. The Basis Passport is a signed, versioned, portable file containing your complete evidence-linked basis state — open lots, disposals with full lot lineage, income events, open decisions. Export it from any saved ClearBasis scan, free, forever — even if you never pay us a cent. Import it anywhere; this page is the whole spec, and anyone (including our competitors) may implement it.

The format

One JSON document. All quantities and USD amounts are decimal strings (never floats — money in floats is how basis dies). Timestamps are ISO-8601 with offsets.

{
 "format": "basis-passport",
 "version": "1.0",
 "generator": {"name": "...", "engine_version": "...", "ruleset_version": "..."},
 "generated_at": "2026-08-22T18:00:00+00:00",
 "open_lots": [
   {"wallet": "coinbase", "asset": "ETH", "qty": "1.5",
    "unit_basis_usd": "1505.00", "acquired_ts": "2023-01-10T12:00:00+00:00",
    "origin_tx": "file.csv:2", "conservative_default": false,
    "evidence": [{"source": "coinbase_csv", "ref": "row:2"}]}
 ],
 "disposals": [
   {"tx_id": "file.csv:9", "ts": "...", "wallet": "coinbase", "asset": "ETH",
    "qty": "1", "proceeds_usd": "1990.00", "kind": "sale",
    "allocations": [
      {"lot_id": "L0001", "qty": "1", "unit_basis_usd": "1505.00",
       "acquired_ts": "...", "conservative_default": false}],
    "evidence": [{"source": "coinbase_csv", "ref": "row:9"}]}
 ],
 "income": [
   {"tx_id": "...", "ts": "...", "wallet": "...", "asset": "ATOM",
    "qty": "5", "fmv_usd": "50.00", "kind": "staking"}
 ],
 "decisions_open": ["D00007"],
 "integrity": {"algo": "sha256", "digest": "…64 hex chars…"}
}

The integrity seal

The integrity.digest is SHA-256 over the canonical JSON of every field except integrity itself — keys sorted, separators (",", ":"), no whitespace, UTF-8. It's a tamper seal, not a secret: anyone can verify a passport wasn't altered in transit, no ClearBasis account required.

canonical = json.dumps({k: v for k, v in passport.items()
                        if k != "integrity"},
                       sort_keys=True, separators=(",", ":"))
assert sha256(canonical.encode()).hexdigest() == passport["integrity"]["digest"]

Semantics that matter

conservative_default: true marks a lot or allocation whose basis was set to $0 because records were missing — the honest floor, never a guess. Importers must preserve the flag: it tells the next tool (and the next accountant) which figures are provable and which are placeholders awaiting evidence. evidence entries point at the source rows/documents each figure came from; an importer that drops them is discarding exactly the part that survives an audit. decisions_open lists unresolved classification questions — a passport is allowed to carry honest uncertainty.

Versioning & license

Semantic versioning; additive fields bump the minor version, breaking changes bump the major. This spec text and the format are free to implement with no license, fee, or permission — attribution appreciated, not required. Corrections and proposals: hello@clearbasis.tax.

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