Ausgleichsmandate

Ausgleichsmandate are compensatory seats in the German Bundestag that serve to maintain proportional representation after the distribution of seats based on the Zweitstimme (second vote). In Germany's mixed-member proportional representation system, each voter has a first vote for a direct candidate in a constituency and a second vote for a party list. If a party wins more direct mandates (Direktmandate) than its share of second votes would entitle it to, the result is overhang mandates (Überhangmandate), and the size of the Bundestag temporarily grows. To restore the overall proportional allocation according to Zweitstimmen, additional seats—Ausgleichsmandate—are allocated to other parties. These compensation seats are distributed so that the total number of seats a party holds corresponds to its share of second votes, thereby preserving proportionality.

The exact number of Ausgleichsmandate and the total Bundestag size are determined by law (Bundeswahlgesetz) and can vary from election to election; the design has evolved since reforms in the 2010s, following court rulings that demanded adjustments to ensure constitutionality and to limit unbounded growth. The result is that the Bundestag size can increase beyond the basic 598 seats (299 constituency seats plus 299 list seats) depending on the pattern of overhang and leveling seats in a given election.

In practice, Ausgleichsmandate function as a corrective mechanism to uphold proportional representation within the German electoral framework. See also Überhangmandat, Zweitstimme, Bundestag.