Wegzugsbesteuerung is often misunderstood. Strictly, it is an exit tax on substantial company shareholdings — and it does not apply to directly held German real estate.
What It Strictly Is
Under §6 AStG, when someone who has been subject to unlimited German tax gives up German tax residency, shareholdings of one percent or more in a corporation are treated as if sold at market value on departure, and the unrealised gain is taxed. A privately held rental property is not within this scope.
What Still Happens When You Leave
The Spekulationsfrist keeps running, Germany keeps the right to tax the property’s rental income and eventual sale (Belegenheitsstaatsprinzip), and your filing status shifts to beschränkte Steuerpflicht. The outcome depends entirely on your new country and the applicable treaty.