Self-service tool · No tax advisory/ case review · Results may vary – please verify
FAQ
Frequently Asked Questions
Answers to the most important questions about KapitalTax, Interactive Brokers tax returns, and the advance lump sum.
General
The self-service tool from KapitalTax is free.
No. KapitalTax is not tax advice and does not replace individual review. All reports must be carefully reviewed by you, and a tax advisor should be consulted in case of doubt.
KapitalTax supports all brokers based on the Interactive Brokers platform: Interactive Brokers directly, LYNX, CapTrader and other introducing brokers.
Use is voluntary. There is no entitlement to availability or specific results.
No, KapitalTax works on a use-case basis. This means: The application is designed for the tax scenarios that many Interactive Brokers users actually encounter in practice. Common and important tax cases are specifically covered, while rare or very special edge cases may not be fully addressed.
Data & Export
Only the Flex export (XML) from Interactive Brokers (or affiliate platforms based on IB). A detailed export guide can be found here.
Log into Interactive Brokers, go to 'Reports' → 'Flex Queries' and create a new Flex Query. Select all relevant sections (Trades, Dividends, etc.) and export as XML. Guide.
First check whether your Flex Query contains all necessary data. If you still find discrepancies, please use the contact form. KapitalTax is continuously being improved. Note: Only technical support is provided. Tax-related individual questions and individual review of provided data/ results are not offered.
Calculations & Tax Law
The calculations are based on the relevant provisions of the German Income Tax Act (EStG) and the Investment Tax Act (InvStG) as well as relevant BMF letters (administrative instructions). KapitalTax technically implements these rules but does not replace tax advice or individual case review. More details can be found on the IBKR Tax Return page and How It Works page.
The output is an automated model/ approximation calculation. It may differ from the actual tax treatment. Please verify all outputs.
German brokers provide a German tax certificate whose details can largely be transferred directly into the tax return. Interactive Brokers typically does not provide such a German tax certificate. Therefore, tax-relevant values must first be calculated and classified from the transaction data.
When the same position was bought multiple times and later sold, it must be traceable which acquisitions are assigned to which sale. In the German tax context, FIFO is the relevant starting point for custodied securities.
KapitalTax uses official ECB reference rates for converting foreign currency transactions. The ECB publishes these reference rates as official exchange rates.
Because many Interactive Brokers users trade not only stocks and ETFs but also options. Topics like writer premiums, paid premiums, reference to the underlying, and cash settlement make the tax classification significantly more complex.
KapitalTax recognizes and processes many typical corporate actions automatically, including stock splits and reverse splits with retroactive split adjustment, as well as spin-offs when a known Fair Market Value is available.
Yes. The report distinguishes different fund types, performs a pre-categorization, and allows the user to make adjustments afterwards. This simplifies further processing for the tax return.
Depending on the portfolio and type of income, KAP, KAP-INV, and SO may be relevant. Good preparation helps to structure the results for this later assignment.
Yes, KapitalTax automatically prepares options transactions from Interactive Brokers for the German tax context. This includes writer premiums, close-outs, cash settlement, expiration, exercise, and assignment. More details on the Options page.
Yes, KapitalTax automatically prepares foreign capital income and the associated withholding tax. This considers country-specific DTA logic, the 25% cap, and where applicable the partial exemption for investment income. More details on the Withholding Tax page.
Options
Yes. KapitalTax considers writer premiums, close-outs, cash settlement, expiration, assignment, and exercise of options and prepares them in a structured way for the German tax context. More details on the Options page.
The writer premium becomes tax-relevant at the time it is received. This is the most important basic rule for Short Call or Short Put.
With assignment, it depends on whether you are Short Call or Short Put. With Short Call, the assignment can lead to delivery of the underlying; with Short Put, to acquisition of the underlying. The previously received writer premium remains a separate tax event.
When a purchased option expires worthless, the costs paid for the option become tax-relevant as a loss.
When a cash settlement occurs instead of delivery of the underlying, the cash settlement is recorded for tax purposes. The costs of the option are considered when determining the result.
According to the official BMF overview of tax changes 2025, the separate loss offsetting circle for derivatives was abolished. Losses can now be fully offset against all capital income again.
Withholding Tax
Yes. KapitalTax prepares foreign capital income and the associated withholding tax in a structured way, reports the creditable withholding tax by country, and considers DTA logic, the 25% cap, and where applicable the partial exemption for investment income. More details on the Withholding Tax page.
No. What matters is not only how much was actually withheld, but also what amount is creditable under the respective double taxation agreement and what the statutory maximum amount in Germany is.
Yes. According to § 32d para. 5 EStG, a maximum of 25% foreign tax on the individual capital income is creditable. This 25% limit is a central component of the German withholding tax logic.
For foreign investment income, the creditable maximum amount is not based on the gross income, but on the taxable investment income remaining after partial exemption. This can result in lower creditable withholding tax than a pure look at the gross income would suggest.
Because German banks often directly consider the creditable foreign withholding tax when calculating the flat-rate withholding tax. Interactive Brokers lacks this typical German tax logic, so the data must first be prepared separately.
Advance Lump Sum
Yes, KapitalTax automatically calculates the advance lump sum (Vorabpauschale) for fund and ETF holdings according to German tax rules. This takes into account relevant market data, distributions, holding period in the acquisition year, and subsequent tax classification. More details on the advance lump sum page.
In practice, it's usually not the mere fund recognition but the complete determination of the data needed for calculation: year-start value, year-end value, distributions, holding period in the acquisition year, and position level.
In practice, a lot-based view is important when a fund position consists of multiple acquisitions. The reason is the different holding period in the acquisition year and the clean connection between position, inflow, and later sale.
In simplified terms, a base return is first determined from the year-start value, 70% of the base interest rate, and the number of units. This amount is capped at the value increase plus distributions, proportionally reduced in the acquisition year, and then reduced by the distributions.
Because § 18 InvStG directly requires these values for base return and cap limit. Without these prices, the calculation cannot be cleanly derived.
In the acquisition year, the base return is reduced on a monthly basis. Therefore, the exact purchase date is relevant for the calculation.
Typically no, because ETCs are generally not investment funds but bonds with commodity reference. BaFin describes ETCs as bonds, not funds.
The partial exemption depends on the fund type and is relevant for the later tax treatment. However, it doesn't change the fact that the complete calculation variables for the advance lump sum must be available first.
They later reduce the capital gain, explicitly by law independent of any possible partial exemption.
Note: KapitalTax assists with the structured preparation of Interactive Brokers data for the German tax context. The content on this page and the reports provided by KapitalTax serve exclusively general informational and preparation purposes and do not constitute individual tax or legal advice. Whether and how individual values should be considered in a personal tax return depends on the individual case.