[3] He worked as a head of department in the Brandenburg Ministry of Labor, Social Affairs, Health, Family and Women and as an employee of the SPD parliamentary group in Potsdam.
[2] Crumbach lives in Potsdam and was married to the social scientist and SPD politician Christine Färber (1964–2018); the couple had two children.
On 11 December 2024, Crumbach was appointed Deputy Minister-President and Minister of Finance and Europe of Brandenburg [de] in the fourth Woidke cabinet.
[13] He rejects discussions about firewalls in parliaments believing that a party ban is "completely the wrong means" to challenge the AfD.
[14] Crumbach advocates for an “Eastern quota” in science, culture and business in order to combat the underrepresentation of East Germans in leadership positions.