Disclaimer: The information in this article provides a general overview and does not claim to be exhaustive. It cannot replace a detailed, individual consultation. TX-Partner assumes no liability for the accuracy, timeliness, or completeness of this information.
An official letter from the tax authority asking about your crypto transactions. That's unusual at first. But also no reason to panic. Let's look at what this means and how to handle it.
01 What does this actually mean?
A supplementary request (in Austria) or information request (in Germany) is a normal inquiry. The tax authority wants more information about a specific matter. In your case: about your crypto activities.
Important to understand: This is not an accusation and not a criminal proceeding. It's an audit. The tax authority has received data (for example through DAC8 reports) and wants to compare it with your statements. Or they simply lack information.
02 Why are you getting this letter?
Crypto inquiries from the tax authority typically have specific triggers. Here are the most common ones:
Typical Triggers:
DAC8 Reports
Since January 2026, crypto exchanges automatically report to tax authorities. If the reported data doesn't match your tax return, inquiries arise.
Collective Information Requests
The tax authority requested user data from exchanges like Bitcoin.de (for 2019-2022). If you were active there, your name could be on the list.
Routine Audit
Sometimes it's simply random sampling or hints in bank statements (e.g., transfers to crypto exchanges).
None of these reasons is inherently problematic. It's about establishing transparency. You can do that.
03 DAC8: The Facts
DAC8 (Directive on Administrative Cooperation) is the EU directive that extends automatic information exchange to crypto assets. Here are the verified facts:
DAC8 Timeline:
October 17, 2023
DAC8 adopted by the EU Council
January 1, 2026
Reporting obligation takes effect - crypto service providers begin data collection
September 30, 2027
First reports to tax authorities (EU-wide)
What gets reported?
The reporting obligation is comprehensive. Crypto service providers report:
- Identification data - Name, address, tax ID, date of birth
- Transaction data - Every purchase, sale, exchange with date and value
- Wallet addresses - All addresses used
- Year-end balances - Value of held crypto assets as of December 31
Germany: KStTG
Germany implemented DAC8 with the Crypto Assets Tax Transparency Act (KStTG), passed on November 6, 2025. A special feature: The reporting deadline in Germany is July 31, 2027 - two months before the EU deadline.
Penalties for Violations
Crypto service providers who don't comply with their reporting obligation risk fines of up to 50,000 EUR per case. This primarily affects the platforms - but the reported data will be compared with tax returns. Discrepancies lead to inquiries.
Sources: EU Commission, German Bundestag
04 Collective Information Requests: The Bitcoin.de Case
Besides DAC8, there's another reason for tax authority inquiries: collective information requests. The best-known example is Bitcoin.de.
Bitcoin.de Collective Information Requests:
Period 1: 2015-2017
First collective information request to Bitcoin.de
Period 2: 2019-2022
Second collective information request - approx. 4,000 accounts affected (from 50,000 EUR annual turnover)
September 25, 2025
Second data package handed over to tax administration
The initiator was the State Office for Combating Financial Crime NRW (LBF NRW). The collected data is distributed nationwide to the responsible tax authorities. This means: If you live in Bavaria but data was collected in NRW, you'll get mail from the Bavarian tax authority.
Source: Tax Administration NRW
05 Austria vs. Germany: The Differences
The terms and legal bases differ between countries. Here's an overview:
| Aspect | Austria | Germany |
|---|---|---|
| Term | Supplementary Request | Information Request |
| Legal Basis | BAO §143 | AO §93 and §208 |
| Typical Deadline | 2-4 weeks | Specified in letter |
| Statute of Limitations (normal) | 5 years | 4 years (7 with negligent shortfall) |
| Statute of Limitations (intent) | 10 years | 10 years |
The processes are similar, but the legal details differ. For specific handling, coordination with a tax advisor who knows the respective country's law is always recommended.
Sources: Austrian Federal Ministry of Finance, German Tax Code
06 What happens if you don't respond?
Ignoring is not a strategy. Here are the possible consequences:
Estimation by the Tax Authority
If you don't provide documents, the tax authority estimates. These estimations typically don't fall in your favor.
Late Payment Surcharges (Germany)
0.25% of assessed tax per month, minimum 25 EUR per started month.
Late Payment Interest (Germany)
0.15% per month = 1.8% per year on the back payment amount.
Criminal Consequences
In case of intent: Tax evasion under §370 AO. The lines between negligence and intent are fluid.
Sources: German Tax Code (§162, §370 AO), Austrian Federal Ministry of Finance
You've received a letter and your tax report shows warnings?
TX-Partner reviews your crypto documentation and prepares it before you submit to the tax authority. No obligations in 30 minutes.
Request Documentation CheckVoluntary Disclosure as an Option
If you realize that mistakes were made in the past, voluntary disclosure can be an option. Important: Voluntary disclosure must occur in time - that is, before the tax authority becomes aware of the discrepancies on its own. The inquiry itself may have already passed this point.
07 What is typically requested?
The requirements are stated in the letter. In our experience, the following are frequently mentioned:
- Tax reports from crypto tax tools - Blockpit, CoinTracking or comparable
- CSV exports - Complete transaction histories from exchanges and wallets
- Wallet addresses - List of all addresses used
- Exchange statements - Official annual statements from platforms
- API credentials - In rare cases for verification
The good thing about this: The requirements are clear. You know exactly what you should deliver. The only question is: Do you have it?
Checklist: Documents you need for your response
Complete Tax Report
From Blockpit or CoinTracking — without warnings, for all requested tax years
CSV Exports from All Exchanges
Transaction histories from every platform used (Binance, Kraken, Coinbase, etc.)
List of All Wallet Addresses
Hardware wallets, software wallets, DeFi wallets — with chain assignment
Exchange Annual Statements
Official statements from platforms (if available)
Bank Statements with Crypto Transactions
Bank receipts for deposits to and withdrawals from crypto exchanges
Typical Deadlines and Procedures: Austria vs. Germany
08 How to proceed
A supplementary request is an information inquiry - not a criminal proceeding. You have time to respond, and the process is clearly structured:
1. Stay calm. A supplementary request is standard. Tax authorities send these routinely, especially since DAC8.
2. Check and note the deadline. Typically 2-4 weeks. If you need more time, request a deadline extension in writing. This is typically unproblematic.
3. Inform your tax advisor. For tax assessment and final submission, you should involve a tax advisor.
4. Check tax report for errors. Open your Blockpit or CoinTracking report. Are there warnings? "Short (Warning)"? "Missing history"? Negative balances? These errors should be corrected before the report is submitted.
5. Have crypto documentation corrected. If the report shows errors, professional help with data cleaning can be sensible. TX-Partner prepares crypto documentation so that the report is audit-ready.
6. Respond in writing. Always in writing, never by phone. Document everything. The tax advisor handles the final submission to the tax authority.
09 Documentation makes the difference
The inquiry itself is rarely the problem. The challenge arises when your tax report doesn't show what it should.
You should know these indicators in tax reports:
- • Negative balances in CoinTracking
- • Divergent balance in Blockpit
- • "Short (Warning)" for sales without purchase history
- • "+ Balancing" with cost basis 0 EUR
- • "Missing history" tags
These indicators point to gaps in transaction history. A clean report without such warnings facilitates all communication.
Imagine submitting a report showing "Negative Balances." The tax authority sees that too. And asks. Then you have to explain why your documentation is incomplete.
Better: Correct documentation BEFORE submission.
10 Preparation instead of reaction
The best time to get your crypto documentation in order is before the letter arrives. The second-best time is now.
Ideally, you've already cleanly prepared your documentation. Then the inquiry is a formality: export report, submit, done.
In reality, we often see: The inquiry arrives, and only then does it become clear that wallets are missing, DeFi isn't fully recorded, or the report shows warnings. This is solvable - but it takes time and the right approach.
What TX-Partner does
TX-Partner doesn't provide tax advice. That's what tax advisors do.
TX-Partner ensures your crypto documentation is correct - before you need to submit it:
- Completely capture all wallets and exchanges
- Reconstruct missing transactions
- Fix warnings and errors in tax tools
- Audit-ready documentation for tax advisors and tax authorities
The result: A clean report that shows exactly what it should. No warnings, no open questions, no attempts at explanation.
In-Depth Questions
How do tax authorities learn about my crypto activities?
Since January 2026, crypto exchanges automatically report to tax authorities under DAC8. Additionally, there have been collective information requests to exchanges like Bitcoin.de for the years 2015-2022. Hints can also come from bank statements (transfers to crypto exchanges) or other tax documents.
Can I request a deadline extension?
Yes, this is typically unproblematic. The request must be in writing and should be justified (e.g., extensive documentation, coordination with tax advisor required, vacation, illness). A deadline extension of 2-4 weeks is frequently granted.
What does "estimation by the tax authority" mean?
If you submit no or incomplete documents, the tax authority may estimate the tax basis (§162 AO in Germany). These estimations are based on the data available to the tax authority and typically don't fall in your favor.
Is voluntary disclosure still possible after receiving a letter?
That depends on the specific case. Voluntary disclosure with exemption from punishment is only possible as long as the offense has not yet been discovered. A supplementary request may, but does not necessarily mean, that discovery has already occurred. This assessment requires coordination with a tax advisor or specialist lawyer.
Does DAC8 also affect DeFi transactions?
DAC8 primarily affects transactions via reporting-obligated crypto service providers (exchanges, custodians). Pure DeFi transactions (without intermediary) are not directly reported. However, all crypto gains are taxable - regardless of whether they are reported or not.
How long do I have to respond to a supplementary request?
The deadline is stated in the letter — typically 2 to 4 weeks. If you need more time, apply in writing for a deadline extension with a concrete reason (e.g., extensive data preparation). This is usually unproblematic and is frequently granted.
What's the difference between a supplementary request and a tax audit?
A supplementary request is a written information inquiry — the tax authority asks for specific documents or explanations. A tax audit is a comprehensive on-site examination where an auditor reviews all relevant records. A tax audit is significantly more intensive and is usually announced in advance.
What if I no longer have the documents (closed exchange, lost wallet)?
For closed exchanges, you can submit a GDPR data request — even insolvent platforms must release data. For lost wallets, on-chain data can be reconstructed via blockchain explorers. TX-Partner assists with reconstructing missing crypto history.
Received a Tax Authority Inquiry?
TX-Partner reviews your crypto history and shows you what to do.
Non-Binding Documentation CheckFurther Information
Co-Founder & Documentation Specialist
Robert Thorn is Co-Founder of TX-Partner, specializing in complex crypto documentation for tax advisors and private investors in Austria and Germany.