In 2012, he was the head of the election headquarters of Ilya Varlamov in the election of the mayor of Omsk.

In 2013 - Deputy Head of the electoral headquarters of Alexei Navalny in the mayoral election in Moscow.
After the election, the head of the electoral headquarters, Leonid Volkov, praised Katz’s work, calling him “the genius of the organization of processes.”
Three years after the campaign, Leonid Volkov said that Katz had been dismissed from headquarters a week before the election due to threats to contact law enforcement in the event of unlawful actions by staff.
According to Katz, there was no dismissal.
According to Ilya Varlamov’s statements, the dismissal attempt was due to Katz’s personal conflict with Chief of Staff Leonid Volkov, but Navalny did not support the attempt to dismiss.

In May 2016, Alexey Navalny, negatively assessing Katz and the experience of working with him, ruled out the possibility of any further interaction and cooperation.
Soon after, Yekaterina Patulina, the former head of the Internet department of Navalny’s headquarters, spoke about the conflict between Katz and Volkov, claiming that the real cause of the conflict was sexual harassment of her by Leonid Volkov.

In 2015, Katz joined the federal council of the "Civil Initiative" party and headed the party’s campaign headquarters for elections to the Kaluga Regional Duma.

In 2016, he headed the election headquarters of the State Duma deputy of the VI convocation Dmitry Gudkov, who in the September 18 elections to the State Duma was nominated for the Tushino constituency from the Yabloko party.
During the election campaign, he created an online platform for conducting the election campaign, which won the "Pollie award" in the nomination “Digital / internet - foreign language”.
The campaign was also awarded the "International - best in Show" award.

In March 2017, Maxim Katz, together with Dmitry Gudkov, launched the United Democrats project, designed to elect democratically minded Muscovites as municipal deputies in the September elections.
The site, created by Katz and Gudkov, helped candidates register, collect signatures, join teams, print campaign materials, and collect money for election accounts.
A total of 3,500 people applied for participation in this project as candidates for deputies, but only those candidates who expressed clear democratic and opposition positions and negative attitude to the incumbent president Vladimir Putin received assistance.
A total of 999 people were nominated, as a result of which 267 became deputies.

Of the 266 deputies supported by the United Democrats project, 177 were nominated by the Yabloko party, making the party the second in the city in terms of the number of deputy mandates.
Commenting on the election results for the party, leader Grigory Yavlinsky called Katz “an effective ally” and noted the youth’s interest in the elections.
Later, in January 2018, Dmitry Gudkov broke off cooperation with Katz due to disagreements regarding the Yabloko part.

In 2019, Maxim Katz participated in the leadership of election campaigns in the Moscow City Duma of Daria Besedina and Anastasia Bryukhanova, employees of City projects.
Daria Besedina was registered, her team raised more than 18 million rubles through fundraising, Daria was supported by a "Smart Vote" of Alexei Navalny and was able to win the election, becoming a deputy of the Moscow City Duma.
In 2012, he was the head of the election headquarters of Ilya Varlamov in the election of the mayor of Omsk.
In 2013 - Deputy Head of the electoral headquarters of Alexei Navalny in the mayoral election in Moscow. After the election, the head of the electoral headquarters, Leonid Volkov, praised Katz’s work, calling him “the genius of the organization of processes.” Three years after the campaign, Leonid Volkov said that Katz had been dismissed from headquarters a week before the election due to threats to contact law enforcement in the event of unlawful actions by staff. According to Katz, there was no dismissal. According to Ilya Varlamov’s statements, the dismissal attempt was due to Katz’s personal conflict with Chief of Staff Leonid Volkov, but Navalny did not support the attempt to dismiss.
In May 2016, Alexey Navalny, negatively assessing Katz and the experience of working with him, ruled out the possibility of any further interaction and cooperation. Soon after, Yekaterina Patulina, the former head of the Internet department of Navalny’s headquarters, spoke about the conflict between Katz and Volkov, claiming that the real cause of the conflict was sexual harassment of her by Leonid Volkov.
In 2015, Katz joined the federal council of the "Civil Initiative" party and headed the party’s campaign headquarters for elections to the Kaluga Regional Duma.
In 2016, he headed the election headquarters of the State Duma deputy of the VI convocation Dmitry Gudkov, who in the September 18 elections to the State Duma was nominated for the Tushino constituency from the Yabloko party. During the election campaign, he created an online platform for conducting the election campaign, which won the "Pollie award" in the nomination “Digital / internet - foreign language”. The campaign was also awarded the "International - best in Show" award.
In March 2017, Maxim Katz, together with Dmitry Gudkov, launched the United Democrats project, designed to elect democratically minded Muscovites as municipal deputies in the September elections. The site, created by Katz and Gudkov, helped candidates register, collect signatures, join teams, print campaign materials, and collect money for election accounts. A total of 3,500 people applied for participation in this project as candidates for deputies, but only those candidates who expressed clear democratic and opposition positions and negative attitude to the incumbent president Vladimir Putin received assistance. A total of 999 people were nominated, as a result of which 267 became deputies.
Of the 266 deputies supported by the United Democrats project, 177 were nominated by the Yabloko party, making the party the second in the city in terms of the number of deputy mandates. Commenting on the election results for the party, leader Grigory Yavlinsky called Katz “an effective ally” and noted the youth’s interest in the elections. Later, in January 2018, Dmitry Gudkov broke off cooperation with Katz due to disagreements regarding the Yabloko part.
In 2019, Maxim Katz participated in the leadership of election campaigns in the Moscow City Duma of Daria Besedina and Anastasia Bryukhanova, employees of City projects. Daria Besedina was registered, her team raised more than 18 million rubles through fundraising, Daria was supported by a "Smart Vote" of Alexei Navalny and was able to win the election, becoming a deputy of the Moscow City Duma.
Maxim Katz