With present (2021) tally rules, the number of seats in the Bundestag is highly volatile. In 2017 it got 709 seats, 111 of them extra-ordinary. The rules may double the influence of a voter who splits the ballot, contrary to a goal of equal influence; increased assembly size is a concomitant. The paper explains when and how this happens. A ballot’s combination of Erststimme and Zweitstimme is information now ignored; the tally is as if they were collected in separate ballot boxes. Faithful accounting requires this information, but there is strong reason to expect it will reduce the 2017 assembly size to the ordinary 598 seats stated in the Federal Elections Act. Tallying 2017 votes with the present rules, but with CDU&CSU as a recognized coalition, reduces the size by 41 seats.