One prominent theme in The Adding Machine is the regulating and alienating effect of manual labor. Many of the characters, especially those who work on Ford's assembly line, spend much of their time like cogs in a machine. After over two decades training his mind to perfect his mindless process, Mr. Zero finds himself unable to socialize organically.

This brings us to a second, tangent theme: the machinization of human bodies at the whims of capitalism. The relationship between Mr. Zero and his corporation is inherently exploitative, turning him into a mindless machine that accomplishes small, discrete computational tasks. This allows his employers to dehumanize him, and ultimately replace him with an even lower-cost adding machine that metaphorically stands in for the subject.

A third theme is the mutability, or potential for change, of humanity's idea of the afterlife. When Mr. Zero dies after an unfulfilling life, he is ushered into a heaven that seems idyllic at first, but which he soon finds mindlessly bohemian and obnoxious. Like a corporation itself, Heaven throws him out because it recognizes him as a poor fit. This event parodies humans' narrow-minded metaphors for heaven, demonstrating that they are all entangled in the unfulfilled hopes and dreams of the living world.