Do you own American stocks? Then you should definitely beware. You may be surprised.

Most people like US stocks. Of course, investing carries some risks. But there's one thing that few people tell you about that can have a significant impact on your wealth. What is it? How do you prevent it, and how do you protect yourself? Find out below.

One of the most well-known concepts is the so-called double tax treaty, which protects investors from having to tax their investment income more than once. But here it is very important to understand what all is covered by this treaty. Most investors are under the impression that this treaty protects them in all respects. They are partly right, because the Czech-US double taxation treaty covers investment income, but only for the lifetime of the investor. This means that if you are building a portfolio that you want to one day leave to your descendants, they may have a problem in the future.