If I'm a tax resident in Germany, do I pay tax on income from international investments?

Yes, if you're considered a tax resident in Germany, you'll be taxed on all your worldwide income, and that includes any earnings from your international investments. To prevent double taxation, Germany has agreements with many other countries, known as Doppelbesteuerungsabkommen (double taxation agreements). Determining your tax residency depends on factors like how long you spend in Germany, so it's always smart to get advice from a tax consultant on this.