Why We're Starting This Blog – And What to Expect
Why this blog?
Because this knowledge doesn't exist in one place.
If you trade through Interactive Brokers and are tax-resident in Germany, you'll quickly notice: the broker provides excellent trading tools, but when it comes to taxes, you're on your own. No automatic withholding, no annual tax certificate, no mapping to KAP form lines.
Thomas and I built BubbleTax because we were facing exactly this problem ourselves. Along the way, we've learned a lot. Connections and edge cases you'd have to piece together from scattered sources, because they're not in any IBKR manual. That's what we want to write about here.
What to expect
Practical knowledge, with worked examples and legal references where needed:
- FIFO across multiple years: Many people think FIFO means "buy price minus sell price." That falls short once you've bought the same stock in different years.
- Foreign currency FIFO: This one surprises almost everyone. USD holdings at IBKR are separate economic assets under German tax law. The dollar outflow alone when buying shares can trigger a taxable FX gain, even without deliberately converting currency.
- Tax buckets: Stocks, ETFs, options, futures – they all go into different loss offset buckets. Which instrument belongs where isn't always obvious.
- ETF classification: IBKR only knows "ETF." German tax law distinguishes InvStG funds, ETNs, ETCs, and special cases. The wrong classification can mean hundreds of euros difference.
- Options & futures: A single trade can create multiple tax events in different tax years. The broker statement doesn't show this.
Why this isn't trivial
With 50 trades per year, you might still manage in Excel. With 500+ trades involving options, multiple currencies, and corporate actions, it becomes error-prone. One mistake in the FIFO chain carries through every subsequent year.
Our goal with BubbleTax: every number in the report must be traceable. Not just a total, but the full derivation, so you can explain to the tax office how it was calculated.
Already available: Webinar recording
Together with WH SelfInvest and stock3, we recorded a webinar: "Trading Meets German Tax Logic." 51 minutes covering the most important pitfalls, from ETF classification to foreign currency FIFO.
→ Read the webinar summary and watch the recording
What's next
We're working on an article series covering each topic in depth, with concrete worked examples from IBKR scenarios. To stay updated, sign up for our newsletter.
Or try it yourself: upload your IBKR data and get a free preview.
Disclaimer: This blog is for informational purposes and does not constitute tax advice. For individual tax questions, please consult a tax advisor.