The Basic Law regulates the legislative powers (Legislative sovereignty) between the federal government and the states. In addition to the exclusive legislation of either the Federation or the Laender for a field of law, Article 72 of the Basic Law opens up the possibility of competing legislation.
The federal states may enact laws in the areas of competing legislation, provided that the federal government does not make use of its legislative right. As soon as the federal government enacts a law, the states are not allowed to create their own laws. The express non-occupation of a legal area (e.g. by repealing an existing law) by the federal government also blocks this legal area for the federal states.
Since the federal government generally makes use of its legislative competence, the states have little room for maneuver. In the tax area, the federal government has competing legislative competence for taxes that are not subject to its exclusive legislation, provided that the federal government is entitled to all or part of the revenue. The federal states are not allowed to have exclusive legislative competence.