We investigate how the rigidity of public contracts influences the frequency of their renewal. Using a dataset of contracts for public–private car parks and employing machine-reading techniques to assess contract rigidity, we find that heightened contract rigidity, particularly in litigation clauses, significantly raises the probability of contract renewal. Our findings indicate that procedural sunk costs and the competitive advantage conferred to incumbents by contract rigidity are key factors contributing to more frequent renewals. This study enhances our comprehension of public contract renewals by emphasizing the significance of political contestability and rigidity, providing valuable insights into optimal strategies for contract renegotiation.