Purpose: The paper aims to estimate the capacity of supreme audit institutions’ (SAIs) audits to deter potentially wasteful year-end procurement spending. It also studies heterogeneous responses to SAIs’ audits depending on whether agencies’ top managers are appointed through a competitive procedure or not. Design/methodology/approach: A letter signed by the head of Chile’s SAI was sent to a hundred randomly chosen agencies two weeks before the end of the fiscal year, with instructions on year-end spending accounting and an audit threat. In addition, a hundred agencies that did not receive the letter were used as a control group. Findings: Agencies that received the letter reduced year-end aggregate procurement spending by 33% relative to controls. Purchases of office supplies, safety equipment, personal care products and paper products experienced the most considerable reductions. The decrease in year-end spending was smaller for agencies with at least one top manager appointed through a competitive procedure. Research limitations/implications: A SAI’s audit threat significantly reduced year-end procurement spending. Larger reductions in agencies headed by political appointees and across categories of goods that have been flagged as likely to be purchased to exhaust the budget suggest the avoided expenditures would have been wasteful. Further research is needed to determine if the net social value of year-end procurement spending deterred by SAIs audits is negative as suggested. Social implications: This paper has implications for the institutional support of SAIs audits and civil service. Originality/value: This paper provides novel experimental evidence of SAIs’ audits’ deterrence power on public agencies’ year-end procurement spending.