Mapping out your crypto assets: why you cannot wait until your next tax return

What the Senate will discuss on Tuesday

The expert hearing in the Dutch Senate revolves around three core points. First: how will actual return be determined for asset categories such as cryptocurrencies? In addition: how will the tax authority deal with sharp price fluctuations within a single year? Furthermore, there is the discussion about capital growth versus capital gains: taxing unrealised value increases, or only on sale?

For investors in bitcoin, ether and other cryptocurrencies, this difference is enormous. Under capital growth taxation, you pay 36% tax on a paper profit you have not yet realised. In addition, this means: if the price drops the following year, you have lost that money to the tax office while your portfolio has already shrunk. Therefore, various parties are pushing for a variant based on actually realised results.

What this means for the average investor

Imagine: over the past few years, you have built up a position in bitcoin and a number of altcoins. Part of it sits on a Dutch exchange. In addition, a part is on a foreign platform. Furthermore, you manage a hardware wallet yourself. For the tax authority, this is one whole: your crypto assets on the reference date.

Under the Box 3 Actual Return Act, you will not only have to declare these assets, but also substantiate them. In addition, you must be able to trace transactions, deposits, swaps and staking rewards. Furthermore, you must be able to prove the origin of funds. That sounds straightforward, but in practice it falls apart on scattered platforms, old email addresses and exchanges that no longer exist.

In short: those who do not start administering now will fall behind. Therefore, more and more investors are choosing to have their crypto assets mapped out by a specialised firm. Not at the next tax return, but this month.

DAC8: why your portfolio is already under scrutiny

The DAC8 directive fundamentally changes the playing field. Since 1 January 2026, crypto-asset service providers (CASPs) are required to collect your customer data, transactions and balances. In addition, this obligation also applies to many foreign platforms as soon as they serve European customers. Furthermore, EU tax authorities work together to automatically exchange this data among themselves.

Concretely, this means: every purchase, swap and transfer you make on an exchange today is recorded by that platform for the tax authority. In addition, the Dutch tax authority receives this information in a structured manner. Therefore, this is the moment to have your own overview. Those who can show their assets with a substantiated report stand stronger in any conversation with the tax authority.

What an asset investigation by Paucitas delivers

As a specialist firm for blockchain investigation, we map crypto assets in full. We combine on-chain analysis with the administration of wallets, exchanges and previous tax returns. In addition, we reconstruct the history of a portfolio: purchases, swaps, transfers between wallets and staking rewards. Furthermore, we deliver a report suitable for the tax authority, an accountant or a law firm.

This report has three functions. First, it provides peace of mind: today you know what you have, where it is and how it came about. In addition, it offers a fiscal basis for Box 3, regardless of the form in which the new act eventually enters into force. Furthermore, it serves as evidence when the tax authority asks questions based on DAC8 data.

For entrepreneurs with crypto assets on the business balance sheet, there is an additional element. A substantiated report supports the annual accounts and the valuation. In addition, it helps in conversations with the bank and during due diligence. Therefore, we increasingly see that an asset investigation becomes part of standard year-end work.

When is it sensible to take action?

Postponing until the Senate is finished is understandable but unwise. The act will come in one form or another regardless. In addition, DAC8 is already active and your transaction history is being recorded by crypto service providers right now. Furthermore, a thorough asset investigation across multiple wallets and exchanges easily takes several weeks. Waiting is no longer an option: those who start this week will have their portfolio in order next month.

Are you unsure whether your situation is complex enough for an investigation? A short intake will provide clarity. We will discuss which platforms you have used, how your portfolio is structured and what documentation is available. Afterwards, you will know whether a full blockchain investigation adds value, or whether a brief overview will suffice.

Mapping out your crypto assets with Paucitas

Box 3 and crypto assets are inseparably linked from today. DAC8 accelerates this process. Therefore, we advise investors not to wait for the next tax return, but to begin now. An asset investigation by Paucitas delivers a substantiated report that holds up both fiscally and legally.

Would you like to know what such a process involves for your portfolio? Get in touch for a no-obligation intake. You can also read more about our approach and methodology on the page about our services for blockchain investigation and asset investigation.

In brief: mapping out crypto assets

• Mapping out crypto assets is essential for Box 3 tax returns, DAC8 reporting, source of wealth verification and court files.
• Paucitas combines client-supplied documents with on-chain analysis to build a complete picture of the assets.
• Wallet recovery with partial access codes is among our capabilities when clients no longer have full access to their own wallets.
• The final report is usable towards banks, the tax authority, law firms and supervisors.
• Starting early prevents bottlenecks at tax deadlines and during court proceedings.

Key terms

Source of wealth is the substantiated explanation of the origin of assets, required by banks and supervisors.

Box 3 is the Dutch wealth tax which also covers crypto holdings; a correct return requires a complete overview.

DAC8 is the European directive that obliges crypto service providers to share customer data with tax authorities.

Wallet recovery with partial access codes is the technical process by which access to a wallet is restored when part of the seed or key is available.

Substantiating crypto assets for Box 3, banks and mortgage lenders

Many private individuals and managing directors have built up crypto holdings across multiple exchanges, wallets and years of transactions. When the Dutch Tax Authority, a bank or a mortgage lender requests substantiation, for Box 3, for a mortgage application or for source of wealth verification, a complete dossier is required. Paucitas maps out your crypto assets independently and manually, so that origin and lawful acquisition can be demonstrated.

When is independent substantiation needed?

• Box 3 tax return: complete inventory of wallets and balances per reference date, with underlying transaction history.
• Mortgage application: substantiation of own funds from crypto, including origin of the initial investment.
• Source of wealth verification: reporting for banks requiring Wwft-compliant evidence of how wealth was accumulated.
• DAC8 reporting: preparation for the European reporting obligation for crypto-asset providers and holders.
• Accountant support: substantiation for annual accounts or for finance departments that need to process crypto positions.
• Director-major shareholder overview: separation of crypto held privately versus in the company, with clear substantiation per entity.

How does Paucitas work?

Instead of automated software licences, Paucitas delivers manual blockchain investigation by human specialists. That means: a traceable chain per wallet, an explanation of any transactions that stand out, and a report that you can submit directly to your accountant, bank, civil-law notary or the Dutch Tax Authority. In cases of partial access codes we first investigate whether wallet recovery is possible before completing the inventory.

Who is this relevant for?

• Private individuals who want to make their crypto assets transparent for Box 3 or for a Dutch bank.
• Entrepreneurs and managing directors who need to verify the origin of crypto wealth for mortgage lenders or compliance departments.
• Accountants and finance departments seeking support in clarifying crypto substantiation.
• Private individuals with a complex transaction history across multiple exchanges, wallets and years.

Reference: see the Belastingdienst guidance on cryptocurrency in Box 3 and the EU DAC8 directive (Directive (EU) 2023/2226). Related on Paucitas: help with crypto fraud.