Everything downstream depends on this
The four countries disagree on rates, methods and forms — and agree completely on one premise: you can demonstrate the full story of every disposal. Gain or loss, holding period, capital or income — all of it rests on records. And the failure mode is predictable: with holes in the history, you end up estimating on conservative (higher) assumptions and over-paying, or facing a query you cannot answer. The most accurate rate table on this site is useless against numbers you cannot reconstruct.
The fields to keep
| Field | Why it matters |
|---|---|
| Date and time | Drives holding periods (the UK’s 30-day rule, 12 months in Australia and the US, one year in Germany). |
| Transaction type | Buy / sell / swap / spend / reward — decides taxability and classification. |
| Token and quantity | Ties the entry to the right asset and cost pool. |
| Fiat value at the time | In your home currency (GBP/AUD/USD/EUR) — the basis of every calculation. |
| Counterparty / platform | Separates exchange, wallet and DeFi origins. |
| Fees | Usually join the cost basis or disposal costs. |
| Wallet address / transaction hash | On-chain verifiability — your reconciliation and your proof. |
Cost basis and holding period
The same token, bought repeatedly at different prices, forces a question at every sale: which lot went? Methods like FIFO and pooled average cost answer it differently, and countries permit or mandate different ones:
- United Kingdom: Section 104 pooling plus the same-day and 30-day rules.
- United States: basis and holding period under property rules — and since 2025, tracked per wallet or account; whatever method you use must be applied consistently.
- Germany: acquisition date decides the one-year test, with FIFO the common matching convention.
- Australia: cost base under CGT rules, with the holding period deciding the 50% discount.
The through-line: pick a compliant method, apply it consistently, and keep the raw records that support it.
Exporting from exchanges and wallets
- Transaction CSV / spreadsheet exports: most exchanges export trades, deposits, withdrawals and fees by date range.
- Annual statements: some platforms produce yearly transaction or profit summaries that map onto filings.
- Read-only API keys: let tax software sync automatically — read-only permissions strictly, and guard the keys.
- On-chain wallets: block explorers and indexing tools export transfers and contract interactions per address.
Reconciling across platforms
The realistic portfolio is a few exchanges, a few wallets and some DeFi. Reconciliation aims at nothing double-counted, nothing missing: pair up cross-platform transfers so your own moves are not booked as disposals, normalise time zones and the pricing currency, and check closing balances against the chain. Dedicated tax software takes much of the drudgery out — but its output is only ever as good as the data you feed it.
How long to keep it
Retention rules differ; the common ranges (each authority’s rule governs):
- Australia: generally five years.
- United States: generally at least three years, longer in specific situations.
- United Kingdom / Germany: per their respective record-keeping rules — cover the assessment look-back period at minimum, and err longer.
Further reading
- Official record requirements: the source lists on the UK · Australia · US · Germany pages.
- Why reconciliation is getting less optional: CARF and automatic reporting.
- Tooling: Choosing crypto tax software.
The earlier, the cheaper
This page covers method, not advice for your circumstances. One warning from experience: exchange history does not stay available forever — platforms shut down, redesign, or truncate exports, and what was not downloaded often cannot be recovered. Export now, not at filing time. Fields and retention per your country’s official requirements.