Where the values in your report come from
Every disposal and reward has to be valued in your tax currency. This page says plainly which sources this version uses, in what order, and what it doesn’t do.
What this version uses
CryptoTaxOwl currently values transactions from your own files and your own entries. It does not include a bundled crypto price dataset yet, and it never fetches prices from a third-party service. Most exchange exports already include a value in your local currency for each buy, sell or reward, so for many people every transaction is covered. Where one isn’t, the calculator lists it so you can enter a value.
The order values are used
- A value in your file. Many exports state the fiat value of each row, for example a subtotal or total in your currency. Values with a precise time take priority over anything else.
- The fiat side of a trade. If you bought crypto with pounds, dollars or euros, the amount you paid is the value.
- The other side of a crypto-to-crypto trade. If you swapped coin A for coin B and one side has a known value, that value is used for both.
- A value you enter. Anything still missing is listed under “Prices” in the calculator for you to fill in, with a note of the source you used.
Each value in the ledger carries a label showing which of these it came from, and the report counts how many came from each source. A missing value is never silently treated as zero. If you choose to accept zero for an item, the report lists it. For a stablecoin with no value, you can opt in to treating it as worth one unit of the currency it tracks, and that assumption is stated in the report.
Currency conversion
When a value is in a different currency from your tax currency (for example a USD value on an exchange when you report in pounds), it’s converted using the euro foreign exchange reference rates published by the European Central Bank. Source: ECB statistics. Conversions between two non-euro currencies are calculated through the euro and are our derived figures, not rates published by the ECB. On days without a published rate, such as weekends and TARGET holidays, the most recent earlier rate is used. The rates are bundled with the calculator as a fixed file, identical for every visitor.
Why we don’t look prices up for you
The easy way to value a transaction is to ask a price service “what was coin X worth on date Y?”. Doing that for each of your transactions would send your holdings and trading dates to that service, and, through it, possibly to others. That would break the promise that your history never leaves your device. So the calculator only downloads files that are the same for everyone, and nothing that depends on what you hold.
A bundled dataset, later
We plan to add a daily price file covering the most widely held assets, downloaded as a fixed set so that it reveals nothing about you. It will only ship once we have a licence that allows it to be redistributed this way. When it does, this page will list the source, licence, coverage and version, and the changelog will record it.
Consistency matters more than precision to the second
Tax authorities generally expect a reasonable, consistent method of valuation, applied the same way across your records; HMRC, for example, says reasonable care should be taken to arrive at an appropriate valuation using a consistent methodology, and that records of the method should be kept (CRYPTO23000). Whatever source you use for values you enter, use the same one throughout and keep a note of it. The report records the methods used so an accountant can see how each figure was reached. See how it works for the full method.