Crypto tax file: which documents you really need

Which documents do you really need for a crypto tax file?

You need four kinds of documents: bank records of your deposits, transaction and annual overviews per platform, a balance overview on the reference date, and substantiation for everything that went outside the blockchain. Anything beyond that is useful but not load bearing.

Those four categories are not arbitrary. They follow the question a reviewing party asks: where did the money come from, what did you do with it, what was it worth at the reference moment, and what happened that I cannot see.

The rest of this blog works those four out as a delivery list. What you do not need: screenshots of rates, printouts from portfolio apps and summaries you made yourself. Those are not traceable and therefore add nothing.

Which crypto tax file records belong to your purchases and deposits?

Your purchases and deposits are covered by the bank records showing that the money you put into crypto came from a demonstrable source. This is the part that is most often incomplete and at the same time weighs the heaviest in a crypto tax file.

• Bank statements of every transfer to a trading platform or payment service provider, with date, amount and counter account.
• Bank statements covering the period in which that money was built up, for example salary, a sale, a gift or an inheritance.
• Underlying records for that source: an employment contract, a deed of sale, a deed of gift or a certificate of inheritance.
• Proof of purchases you made with cash or through a private individual, if there are any.
• An overview of all payment service providers appearing in your statements, including under outdated names.

That last point yields the most in practice. We regularly see that an old debit to a processor with a neutral name is the only indication of a platform someone no longer remembered.

Which records belong to your balance on the reference date?

Your balance on the reference date requires, per address and per platform, a specification of the quantity you held at that moment, with its value according to a publicly available source at that same time. A total amount without that breakdown is not substantiation in a crypto tax file.

• A balance specification per trading platform on the reference date, preferably the official annual overview from the platform itself.
• Per own wallet the address and the quantity per token on the reference date, traceable from the bookings up to and including that date.
• The rate source used and the exact time at which you took that rate, recorded before you make the calculation.
• For tokens that were barely traded: the data your valuation rests on, and a range instead of a single figure.

For the questions most often asked about this in practice, our overview of verification questions around box 3 and crypto is a useful addition.

Which records belong to transactions that are not on the blockchain?

For transactions outside the blockchain you need records from the counterparty, because no booking exists that you can point to. Internal conversions within an exchange, staking proceeds credited inside the platform and private purchases all fall into this category.

• The complete transaction overview from the platform, including internal conversions and credits.
• Confirmation emails of transactions you cannot find in the overview.
• For a private purchase: a written record with date, quantity, amount and the method of payment.
• For a platform that has been shut down: every file you ever downloaded, even if it is incomplete.

This category is the reason a file can sometimes not be made watertight. That is not a failure but a given, and it belongs in the overview as a reservation instead of being papered over.

How do you assemble the crypto tax file step by step?

You assemble the file in eight steps, and you only start calculating once the collecting is finished.

1. Determine the purpose and the reference date, and note which year or years it concerns.
2. Request bank statements covering at least the whole period in which you bought crypto, and longer if the source of the money lies further back.
3. Make a list of every payment service provider and every platform appearing in those statements.
4. Download per platform the complete transaction overview and the annual overview, also for accounts you no longer use.
5. Note per own wallet the address and collect the transaction hash of every booking that belongs to the question.
6. Record what happened outside the blockchain and find the counterparty records to go with it.
7. Calculate per address and per platform the balance on the reference date and value it against the source chosen in advance.
8. Have holdings, origin and valuation established and recorded independently, so that the overview can be rechecked without your explanation.

Steps two and three together cost an afternoon and determine whether the rest of the steps work at all. Whoever starts there rarely has to start over. For the bank version of this route, our step by step plan for an origin file your bank can check line by line is the follow up.

What do you do if a document is missing or a platform no longer exists?

In a crypto tax file a missing document is not the end. If a document is missing, you do not fill the gap with an assumption but name it as a gap and find a second trace to go with it. A missing annual overview can often be compensated with the bank deposits on one side and the outgoing bookings to your own wallet on the other.

If the platform no longer exists, three traces remain: your bank statements, your mailbox and the blockchain. In many files that is enough to make the size plausible, albeit with a wider margin. What does not work is a reconstruction from memory, because that survives no review at all.

Paucitas uses no automated analysis software, in any role whatsoever. The investigation is done manually on the basis of publicly accessible block explorers. Every transaction and every transaction hash is verified one by one before it is included in a report.

What does Paucitas not do in a crypto tax file?

Paucitas substantiates, verifies and maps, and does not assess how your holdings should be treated for tax purposes. That boundary is the core of the division of roles and is stated explicitly in every overview.

• Paucitas gives no tax or legal advice.
• A report by Paucitas is limited to factual observations and the investigation of those observations.
• Paucitas holds no funds itself and carries out no transactions on behalf of clients.
• Transactions outside the blockchain, such as cash payments or internal bookings within an exchange, are not visible in blockchain data. They are only included if underlying documents are available.
• Paucitas does not independently establish who is behind a crypto address. What is recorded is which service provider or party holdings went to, so that this information can be followed up through the channels intended for it.
• Paucitas makes no commitment about the outcome of an investigation.

For a tax judgement on your return we refer you to a tax adviser, and for a legal judgement to a lawyer or the competent authority. Paucitas also conducts no correspondence with the tax authorities on your behalf.

What can you do yourself and when is that not enough?

You can do the collecting entirely yourself, and that is also the largest part of the work on a crypto tax file. With one platform, one wallet and a manageable period you will probably get all the way with the delivery list above.

It is no longer enough as soon as a platform among them has been shut down, as soon as holdings have been moved across several networks, as soon as you can no longer survey a period, or as soon as the tax authorities ask further questions after your first answer. From that point an independent finding is the shortest route.

Data is supplied digitally or at the office. Per case a delivery list is provided which states what data is needed. Where necessary Paucitas guides the collection and delivery of that data.

Paucitas usually responds within a few minutes to an hour and in virtually all cases on the same working day.

What is in the report and how long does an investigation take?

A report by Paucitas follows a fixed structure: reason and description of the assignment, the questions, the scope, the starting points, the data supplied, the sources consulted, the method in outline, verification and quality assurance, reservations and limitations, findings per part, a chronological overview, analysis and coherence, conclusion, statement of independence and appendices. Not every report contains all parts, and the structure is matched to the purpose you need it for.

An investigation by Paucitas takes, depending on the size of the file and the urgency, between one working day and two weeks. An urgent report can be delivered within one working day and in exceptional cases on the same day. A regular investigation is usually ready within three working days. In files with many transactions, several wallets or missing history the lead time rises to around two weeks. A surcharge applies to urgent assignments.

Paucitas works with a fixed rate based on your situation. Sometimes we apply an hourly rate by agreement, but the hours are always fixed in advance, so that you never face surprises. No investigation is started before the costs have been discussed and agreed.

Where does the work of the tax authorities begin and where does that of Paucitas?

The Dutch Tax Administration assesses whether your assets were declared correctly and can send a request for information about that, while Paucitas establishes what factually existed and where it came from. You give the answer to the request yourself, with the crypto tax file as substantiation.

We wrote earlier about the European reporting rules for providers of crypto services in our contribution on DAC8 and the reporting of crypto balances, with the source references there. For the wider context the European Commission publishes on that framework and the European Central Bank on crypto assets in the euro area.

If you want to know whether your crypto tax file is complete, you can go through the delivery list together calmly in a free intake. We name what is missing and are honest about what can no longer be established. More about this service is on proving the origin of assets.

Date of last revision: 31 August 2026.