Keeping your transaction records
- Author
- CRYPTO PORT Editorial
- Published
- Updated
- Reading time
- 6 min
In short
Save your transaction history yourself, before it becomes unreachable. Exchanges limit how far back you can view, and a service that shuts down takes its records with it. How long records must be kept, and what counts as a record, are set by rules — check the National Tax Agency's guidance and a tax professional.
Key points
- Exchanges usually cap how far back history can be viewed or exported
- Save it before a shutdown or account closure puts it out of reach
- Wallet transfers and DeFi activity count too, not just exchange trades
- Retention periods are set by the rules — check National Tax Agency guidance
Definition
Retaining records of purchases, swaps, transfers and rewards as the evidence behind your calculations and your return.
What derails a crypto tax return is usually missing history, not difficult arithmetic. An exchange you used three years ago has closed; a CSV export only goes back twelve months — and now you cannot establish what an asset cost you. Being unable to evidence a cost basis can force you onto an unfavourable assumption, which makes records almost as valuable as the assets themselves.
Worth keeping: exchange trade and deposit/withdrawal history and annual statements; wallet transfer records (transaction hashes make these traceable); staking and lending reward receipts; and DeFi swaps, deposits and withdrawals. Bank records of yen moving in and out are useful for cross-checking.
Exporting quarterly is more reliable than one annual scramble. Name files consistently — year, venue, type — and hold them in two places, cloud and local. Cloud alone fails if an account is locked; local alone fails when a drive does.
Backing up history is not the same as backing up a seed phrase. Never write a seed phrase or private key into a record-keeping file. Leaked history is embarrassing; a leaked key means the assets are gone. Retention periods and the scope of required documents are set by rules that get amended, so confirm the current position with the National Tax Agency's guidance and a tax professional.
Watch out for
- · This page is a general orientation, not tax advice
- · Never store a seed phrase or private key inside a records file
- · Specific requirements such as retention periods do change — check with the National Tax Agency and a tax professional
Frequently asked questions
If a calculation tool holds my data, can I delete the original CSVs?
Keep the originals. If the tool changes, shuts down, or turns out to have mis-imported something, you cannot recalculate without them. Ask a tax professional what documentation may be required as support.