Double Taxation Agreement

A double taxation agreement (DTA) is a treaty between two countries in which they agree not to both tax each other's residents for the same income or wealth. 

DTA's benefit you because they help you avoid paying taxes on the same assets and income in more than one country. Typically, taxes levied by one of the two countries can be deducted from tax liability in the other country. In this case, you will normally only pay the difference between the (lower) tax levied in one country and the (higher) tax levied in the other country. However, the way that taxes are shared may differ between individual DTAs.

Switzerland currently maintains double taxation agreements with around 70 countries. In German, a DTA is known as a Dop­pel­be­steue­rungs­ab­kom­men (DBA).

DTAs most widely apply to income tax. However, a DTA may also cover the taxation of wealth, property, and retirement assets such as pension fund benefits or the Swiss pillar 3a, among others.

More on this topic:
Quasi-residence definition
Swiss tax forum