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The uncomfortable truth
Good record-keeping practice is unremarkable: capture the event while it is in front of you, keep the original untouched, and write down what you assumed. Documentation that survives the year costs five minutes at the time. The sections below cover where it tends to break down in practice.
Price data can be reconstructed from historical sources. A missing export from a venue that has since been acquired, or an exchange that no longer answers email, cannot. Prevention is almost entirely a matter of capturing things while you still can.
The minimum viable record
For every taxable event, five things. Not ten — five.
| # | Field | Why it cannot be recovered later |
|---|---|---|
| 1 | Date and time, with timezone | Determines the tax year and the ordering of same-day events |
| 2 | What you sent | Quantity and asset |
| 3 | What you received | Quantity and asset, including any change in token |
| 4 | Market value of what you received, that day | Usually recoverable, but only if you recorded which source you used |
| 5 | Fee paid, and in which asset | Often omitted from exchange statements entirely |
If a fee is charged in a token other than the one you paid in, record both. Conflating them is a small error that compounds across hundreds of trades.
Value on the day
Income events need a price at the moment of receipt, and the honest answer is that different sources will give you different numbers.
What matters most is not precision. It is that you use one consistent source, record which one it was, and apply the same rule to every event in the period. A figure you can explain is worth more than a marginally more accurate figure you cannot.
Record the source alongside the number. A price with no source cannot be reconciled against anything else. A price with a source and a timestamp can be defended.
Where records break
Every category below is a documentation problem rather than a calculation one, and every one of them is visible while it happens.
Venues that disappear
Exchanges are acquired, fail, or abandon retail customers. Historical exports become harder to obtain over time, not easier. Anything you still need should be captured now, while the endpoint works.
Export limits
Several venues cap how far back an export reaches, typically to a year or less, and quietly truncate anything older. If you have not exported before the window closes, that data is gone.
Lost account access
Two-factor devices replaced, email accounts closed, phone numbers recycled. Your own records are the only thing that survives this, and the venues generally will not help after the fact.
Staking logs
Auto-compounding strategies frequently produce no visible transaction at all. If you do not log them, there is no record that the income ever existed.
Files versus screenshots
Keep the original export. Screenshots are useful as a secondary check but they are lossy: they drop the exact figures, they do not survive a row count, and they cannot be reprocessed if you discover a mistake.
A sensible arrangement is the raw export, untouched, alongside whatever working files you produce from it. If you ever need to show that a number came from a real record, that pair is what does it.
Other people involved
If anyone else touches your accounts — a bookkeeper, a preparer, a trading partner — they need the raw exports, not a summary someone typed from a dashboard. The summary cannot be audited and often cannot be corrected.
A short yearly routine
- Export the full year from every venue, not just the recent period.
- Confirm each file opens and covers the dates you expect.
- Log any income event your venues did not report.
- Keep the raw files somewhere that is not the exchange itself.
- Note which price source you used, so it is consistent across the period.
That is an afternoon of work once a year, and it is the difference between a report you can answer questions about and one you cannot.
Next: when the numbers do not reconcile