IBKR Tax Return – Guide
Interactive Brokers does not issue a German tax certificate. In four steps and under ten minutes, you still get to your finished Anlage KAP.
IBKR is based in Ireland and is not a German credit institution, so the broker withholds no Abgeltungsteuer and issues no annual tax certificate per § 45a EStG. You declare your capital income yourself. BubbleTax handles the entire calculation: from your IBKR XML it produces a tax report with direct KAP line references. The same applies to introducing brokers using IBKR as custodian: LYNX, CapTrader, BANX, MEXEM, AGORA Direct, WH SelfInvest.
- 01Set up Flex Query and export XML
At IBKR, the data export is called a Flex Query. Once created, you reuse it per tax year.
- 02Upload all XML files to BubbleTax
Drag and drop all years together, not just the current one.
- 03Review the tax report
Per tax year, all relevant amounts: gains, losses, dividends, interest, withholding tax, advance lump sums.
- 04Transfer values to your tax return
From the BubbleTax summary into ELSTER, WISO Steuer, SteuerSparErklärung or your software of choice.
How the four steps fit together
Once set up, the process repeats per tax year in the same order.
- 01
Set up the IBKR Flex Query and export XML per year.
- 02
Upload all XML files to BubbleTax.
- 03
Review the tax report, read off the KAP lines.
- 04
Transfer values to ELSTER or your tax software.
Watch video tutorial on YouTube
Each step in detail
Setup is one-time. Everything else repeats per tax year in under ten minutes.
- 01
Set up Flex Query and export XML
At IBKR, the data export is called a Flex Query. Once created, you reuse it per tax year.
In the IBKR Client Portal under Performance & Reports → Flex Queries → plus icon next to Activity Flex Query. Setup takes five to ten minutes; each subsequent export runs in seconds.
- 02
Upload all XML files to BubbleTax
Drag and drop all years together, not just the current one.
BubbleTax processes the data fully automatically: FIFO per § 20 Abs. 4 EStG, EUR conversion at ECB daily rates, withholding-tax crediting, loss offsetting. Usually under one minute.
- 03
Review the tax report
Per tax year, all relevant amounts: gains, losses, dividends, interest, withholding tax, advance lump sums.
The report contains a tax summary with line references for Anlage KAP, KAP-INV and where applicable Anlage SO. Plus detail tables per transaction.
- 04
Transfer values to your tax return
From the BubbleTax summary into ELSTER, WISO Steuer, SteuerSparErklärung or your software of choice.
Each amount is assigned to a specific KAP line. You just type, no calculation needed.
Flex Query: the seven sections
BubbleTax requires exactly these seven data sections with the listed settings. In each section, all fields must be enabled manually; IBKR sets them inactive by default.
| # | Section | Setting |
|---|---|---|
| 1 | Cash Report | with currency breakout enabled |
| 2 | Complex Positions | no special setting needed |
| 3 | Statement of Funds | with currency breakout enabled |
| 4 | Corporate Actions | select Detail |
| 5 | Open Positions | select Summary |
| 6 | Trades | select Execution, not Order |
| 7 | Transfers | select Transfer |
Enable fields per section manually
In each of the seven sections, you must check every field individually. They are disabled by default. Save after each section, otherwise the settings are lost.
What the tax report contains
The BubbleTax report is structured so you can use it as evidence for the tax office.
- Tax summary
Direct line references for Anlage KAP, KAP-INV and Anlage SO.
- Asset-class breakdown
Stocks, ETFs/funds, options, futures, CFDs reported separately.
- Dividends, interest, securities lending
Including substitute dividends (PIL) and correct classification.
- Withholding-tax overview
Creditable amounts per DBA cap by source country.
- Corporate actions
Splits, spin-offs, mergers with quantity and cost-basis adjustment.
- Foreign-currency gains and losses
Computed via FIFO per account and currency.
- Detail tables per transaction
Full traceability for every single booking.
- Open positions at year start and end
So the tax office can verify the FIFO chain.
Avoid common mistakes
We see these mistakes regularly with new users. Checking before upload saves time.
- Only exported the current year
Without prior years, BubbleTax cannot calculate the FIFO chain and acquisition costs. Always export all available years.
- Exported CSV instead of XML
BubbleTax requires the XML export of the Activity Flex Query, not CSV.
- Fields in section not enabled
By default, all fields at IBKR are disabled and must be checked manually.
- Selected Order instead of Execution for Trades
FIFO requires the execution level, not the order level.
- Did not export January of the following year
Interest bookings at IBKR sometimes occur only in early January but belong to the prior tax year (10-day rule per § 11 EStG).
BubbleTax is software for the automated processing of IBKR account data under German tax law. We are not a tax advisory firm. Final responsibility for the correctness of the values entered in the tax return lies with you. For complex constellations (business assets, foreign accounts, special cases) we recommend consultation with a tax advisor. The generated report is suitable as evidence for the tax office.