Kudumbasthan’s premise taps into an evergreen theme in Tamil cinema, which is the struggles of a middle-class protagonist trying to make ends meet. The film’s title itself evokes memories of classics from filmmakers like Bhagyaraj, Visu, and actor Saravanan, who have explored similar themes in their comedy dramas across generations. The story revolves around Naveen (Manikandan), a typical middle-class youngster from a small town in Coimbatore, who is newly married to Vennila (Saanve Megghana). Naveen works as a designer at a local marketing company, earning just enough to sustain their modest life. Meanwhile, Vennila prepares for the UPSC exams while managing household responsibilities and battling caste-based discrimination from her mother-in-law. Their lives take a turn when Naveen, in a moment of self-respect, slaps a client and loses his job. What follows is a downward spiral of financial struggles, debt, and deception, with no apparent way out.