Foreign Currency Gains
As soon as you hold USD or another foreign currency and spend it, an FX position arises. Taxable, even without converting back to EUR.
You sell a US stock and receive 10,000 USD. Two months later, you use it to buy Apple. No gain? Actually yes: if the dollar rose in the meantime, your 10,000 USD are now worth more euros than at inflow. That is a taxable foreign-currency gain under § 20 Abs. 2 Nr. 7 EStG. Most IBKR users find out only when filing their tax return.
- 1.January: inflow from stock saleECB rate 1.10+$10,000
- 2.USD value at inflow10,000 ÷ 1.10 · acquisition of USD holdings+€9,090.91
- 3.March: outflow for Apple purchaseECB rate 1.05−$10,000
- 4.USD value at outflow10,000 ÷ 1.05 · disposal of USD holdings−€9,523.81
- =→ Foreign-currency gain€9,523.81 − €9,090.91 · taxable, even without converting back+€432.90
How the FX gain in line 19 emerges
BubbleTax runs a separate currency FIFO per account and currency. Every inflow and outflow is valued at the ECB rate of the booking day.
- 01
Per currency and account, a FIFO stack is built: each USD inflow lands as a lot with date and ECB rate.
- 02
Each outflow draws the oldest lots, comparing their original ECB rate with the current rate.
- 03
Difference × quantity yields the FX gain or loss per outflow booking.
- 04
Aggregated per tax year in Anlage KAP line 19 (interest-bearing accounts, § 20 EStG) or Anlage SO (non-interest-bearing, § 23 EStG).
Why even a stock purchase triggers FX gains
This is the point most people miss. You don't have to consciously exchange currency. As soon as you buy a stock with your USD holdings, dollars flow out. For tax purposes, that is a use of your foreign currency, a disposal-equivalent transaction.
Legal basis: every outflow from an interest-bearing foreign currency account counts as a disposal-equivalent transaction (Rn. 131 BMF, § 20 Abs. 2 Satz 2 EStG). Whether the dollars are converted back to EUR or not is irrelevant.
Your dollars are an independent asset
From the tax authority's perspective, your USD holdings at IBKR are independent economic assets, like stocks or ETFs. FIFO applies here too. Anchored twice: Rn. 131 BMF for interest-bearing accounts and § 23 Abs. 1 Nr. 2 Satz 3 EStG for non-interest-bearing.
For IBKR accounts (interest-bearing), foreign-currency gains fall under § 20 Abs. 2 Nr. 7 EStG (capital income, Anlage KAP). For non-interest-bearing accounts, § 23 Abs. 1 Nr. 2 EStG applies (private disposal with 1-year holding period, Anlage SO). BubbleTax detects the account type automatically and applies the correct calculation. For interest-bearing accounts, Rn. 131 BMF additionally applies.