Reconstructing Missing Crypto History

Blockpit displays a "Missing History" warning for one or more assets. This may sound harmless, but it has massive implications for tax calculations: without a complete transaction history, Blockpit sets the cost basis to zero euros. The result is fictitious gains that never actually occurred. This article shows you step by step how to reconstruct missing crypto history and restore your crypto documentation to a solid foundation.

01 The Problem: Missing History in Blockpit

When Blockpit displays a "Missing History" warning for an asset, it means: there is a receipt for this asset (e.g., a deposit to an exchange or wallet), but the previous transaction documenting the acquisition is missing. Blockpit cannot trace where the asset came from or what it originally cost.

The consequence is severe: in this case, Blockpit sets the cost basis to zero euros. When sold later, the entire proceeds are calculated as profit, even though you purchased the asset at a specific price.

The more assets affected, the more distorted the entire tax report becomes. For portfolios with many transfers between exchanges and wallets, the sum of fictitious gains can quickly reach five figures.

02 Why Is the History Missing?

The causes of missing history in Blockpit can be divided into five typical categories. Often, several occur simultaneously.

• Missing Exchange Imports – Old accounts on exchanges that are no longer actively used were never imported into Blockpit. This often affects the first exchange where someone bought crypto.
• Missing Data Sources – Exchanges and wallets that were never imported into Blockpit. Older exchange accounts or wallets on chains that the user forgot are particularly often missing.
• Incomplete Wallet Tracking – Anyone who moves assets across multiple chains (Ethereum, Solana, Polygon, Arbitrum) must record each chain separately in Blockpit. If a chain is missing, so are the associated transactions.
• Manual Entries & Auto-Balancing – Users try to close gaps with manual entries or Blockpit's "auto-balancing" function. Both create transactions with a cost basis of €0, which visually solve the problem but worsen it for tax purposes.
• Bridges and Wrapped Tokens – Cross-chain bridges technically create a new transaction on the destination chain. If Blockpit doesn't correctly recognize the bridge transfer as a link, it appears as if the asset appeared out of nowhere on the destination chain.

Quelle: Blockpit Help Center

03 How to Identify Missing History

Missing history manifests in Blockpit at multiple levels. The earlier you recognize the signs, the more precisely you can correct them.

• "Missing History" Warning on Assets – Blockpit marks affected assets directly in the dashboard. This is the most obvious indicator.
• Unrealistically High Gains in Tax Report – If the calculated gain is significantly higher than expected, a missing cost basis is often the cause. Check the largest gain positions individually.
• Negative or Missing Cost Basis – Some assets show a cost basis of €0 or negative holdings. Both indicate missing incoming transactions.
• Assets Appear "Out of Nowhere" – If an asset suddenly appears in the portfolio without a documented purchase transaction, the origin is missing. This often affects transfers from external wallets or exchanges.

04 Step by Step: Reconstructing History

Reconstructing missing crypto history follows a clear sequence. The more systematically you proceed, the fewer gaps remain.

Step 1: List All Sources

Create a complete list of all exchanges, wallets, and DeFi protocols you've ever used. Also consider platforms you only used briefly or years ago. Typical forgotten sources:

• First Exchange – Where did you buy crypto for the very first time? Bitcoin.de, Bitpanda, Coinbase?
• Intermediate Exchanges – Did you transfer assets to another exchange to buy specific altcoins? Binance, KuCoin, Gate.io?
• Hardware Wallets – Ledger, Trezor, or other cold wallets where you stored assets long-term.
• DeFi Protocols – Uniswap, Aave, Curve, Lido, Jupiter, and other protocols you've interacted with.
• Multi-Chain Wallets – MetaMask, Phantom, Rabby with activity on various chains.

Step 2: Obtain CSV Exports

For each identified source, you need the transaction data. For active exchanges, you can download CSV exports directly. For inactive exchanges or exchanges where you no longer have access, there are alternatives:

• Active Exchanges – Log in and export the complete transaction history as CSV. Make sure to select the entire period, not just the current year.
• Inactive Accounts – Many exchanges allow exports even for inactive accounts as long as the account still exists. Reset the password if necessary.
• GDPR Data Request – If the normal export doesn't work, you can submit a data request under Art. 15 GDPR. The exchange is obligated to provide your stored data.

Step 3: Check On-Chain Data

For DeFi transactions and wallet activities, blockchain explorers are the central source of information. Every transaction is permanently stored on-chain and can be traced:

• Etherscan – For Ethereum and ERC-20 tokens
• Solscan – For Solana and SPL tokens
• Arbiscan – For Arbitrum
• Polygonscan – For Polygon
• BscScan – For BNB Chain

Enter your wallet address in the respective explorer and check the transaction history. Compare this with the transactions recorded in Blockpit. Every transaction visible in the explorer but missing in Blockpit must be added.

Step 4: Import into Blockpit and Trigger Recalculation

Import the obtained CSV files into Blockpit. Pay attention to the correct format – Blockpit offers its own import template for each exchange. After importing, it's important to manually trigger the recalculation. Blockpit doesn't automatically update the tax calculation after each import. The recalculation button is located in the tax report section.

Step 5: Check Manual Entries and Auto-Balancing

Check all manual entries and auto-balancing transactions in Blockpit. Entries with a cost basis of €0 should be replaced with properly documented transactions – based on on-chain data or CSV exports. Blockpit's auto-balancing visually resolves the "Missing History" warning, but the cost basis remains at €0, which distorts the tax calculation.

Quelle: Blockpit Help Center

05 Special Cases

Some situations require more effort than a simple CSV import. Here are the most common special cases and how to handle them.

Closed Exchanges (FTX, Mt.Gox, etc.)

For exchanges that no longer exist or were closed due to insolvency, regular data export is no longer possible. There are still ways:

• GDPR Data Request to Insolvency Administrator – In many cases, user data is stored with an insolvency administrator. A formal GDPR request can provide access to your own transaction data.
• Personal Records – Email confirmations, screenshots, or old CSV exports you saved locally can serve as proof.
• On-Chain Data – Deposits and withdrawals to and from the exchange are traceable on-chain, even if the exchange no longer exists. However, trades within the exchange are off-chain and therefore not reconstructible via blockchain explorer.

Very Old Transactions (2015-2018)

Transactions from the early years of crypto adoption are particularly difficult to reconstruct. Exchange interfaces and export formats have changed multiple times since then, and some platforms no longer exist. However:

• Blockchain Explorer – On-chain transactions are immutable and fully viewable even after years. Historical prices can be determined via CoinGecko or CoinMarketCap.
• Historical Prices – For manual import into Blockpit, you need the rate at the time of the transaction. Historical price data is freely available on multiple platforms.
• Manual Entries – Blockpit allows manual transaction entries. For individual, clearly traceable transactions, this is the pragmatic solution.

DeFi Protocols Without Blockpit Integration

Not every DeFi protocol is directly supported by Blockpit. For protocols without integration, there are two approaches:

• Manual CSV Import – Create a CSV file in Blockpit's standard format and enter the transactions manually. The necessary data (timestamp, token, amount, rate) can be found via the blockchain explorer.
• Wallet Tracking – If you've entered the wallet address in Blockpit, Blockpit automatically recognizes many DeFi transactions. However, check whether all transactions were correctly classified – especially for complex interactions like flash loans or composable strategies.

06 The Logic Chain: Why Crypto Documentation Is Critical

Missing history is not an isolated problem. It stands at the beginning of a chain that runs through the entire tax calculation.

If the transaction history has gaps, Blockpit calculates with a cost basis of €0. Any tax calculation based on this is incorrect. And since DAC8, the tax authority can compare the reported exchange data with the tax return. Incomplete crypto documentation can then lead to inquiries.

Quelle: EU-Amtsblatt, Directive (EU) 2023/2226

07 What Missing History Means for Your Tax Return

Missing history is not just a technical problem in Blockpit. It has direct tax consequences that become increasingly severe with growing portfolio size and tightening regulations.

Since DAC8, tax authorities have the ability for the first time to systematically compare reported exchange data with the tax return. If you discover missing history in the tax report after having already submitted a return, you should take the correction obligation under Section 153 AO (German Fiscal Code) seriously. A proactive correction is typically more favorable than a subsequent audit by the tax authority.

08 When Professional Help Makes Sense

Reconstructing missing crypto history is doable yourself in simple cases: import a forgotten exchange, upload a few CSV files, trigger recalculation. However, with more complex portfolios, the effort quickly becomes exponential.

Professional support for crypto documentation makes sense when one or more of the following criteria apply:

• Many Sources – More than 10 exchanges, wallets, or DeFi protocols over several years.
• Complex DeFi Usage – Liquidity pools, yield farming, bridges, wrapped tokens, staking across multiple chains.
• Multi-Year Gaps – Transactions from 2017 or 2018 that were never documented and must now be caught up.
• Closed Exchanges – Platforms like FTX where regular data export is no longer possible.
• Manual Entries with Zero Cost Basis – Transactions were created manually or via auto-balancing with a cost basis of €0 and must be properly documented.
• Errors in Tax Report – The calculated gain significantly deviates from reality and the cause is not immediately apparent.

TX-Partner specializes in exactly these cases: preparing the transaction history in the crypto tax tool completely and comprehensibly. TX-Partner does not offer tax advice, but rather the crypto documentation that tax advisors and tax authorities need as a foundation.

If you're unsure whether your case requires professional support, a non-binding documentation check is the fastest way to gain clarity. In 30 minutes, we assess how extensive the reconstruction is and what effort is realistically involved.