Corruption is the abuse of public power or position for private gain. It ranges from small bribes demanded at a permit office or for a utility connection to large-scale schemes in which political and business elites divert public money. Petty bribery is the form that is best measured: in the median country among 139 with survey data, about 17% of people who had contact with a public official in the past year paid a bribe or were asked for one. Businesses face it too, especially when they need utility connections, permits, licences or tax services. Large-scale corruption is closely tied to illicit financial flows, money that is illegal in its source, its transfer or its use and that leaves countries through trade misinvoicing, tax abuse, crime or theft. UNCTAD estimated in 2020 that illicit capital flight from Africa averaged about $88.6 billion a year, equal to 3.7% of the continent's GDP.
The burden is uneven. Bribery is most common in low-income countries, where the median rate among people dealing with officials is 27%, compared with 9% in high-income countries, and the median share of businesses affected is 18.6% in low-income countries against 2.4% in high-income countries. Bribery can undermine trust in public institutions, and it raises the cost of doing business, distorts competition and discourages investment. When public money leaks away, less is left for public services: in African countries with high illicit outflows, governments spent 25% less on health and 58% less on education than countries with low outflows. Corruption also endangers those who expose it: of the 829 journalists killed outside conflict zones since 2012, 150 were reporting on corruption-related stories.
How corruption is measured
Corruption is largely hidden, so no single number captures it. SDG target 16.5 calls on countries to substantially reduce corruption and bribery in all their forms, and target 16.4 to significantly reduce illicit financial flows by 2030. Four kinds of measurement are used, each covering a different part of the problem:
Bribery experienced by people
SDG indicator 16.5.1 is the share of people who had at least one contact with a public official in the previous 12 months and who paid a bribe or were asked for one. It comes from household surveys and reflects direct experience rather than opinion, but it does not capture grand corruption involving political and business elites.
Bribery experienced by businesses
SDG indicator 16.5.2 applies the same question to firms. The World Bank Enterprise Surveys ask firms whether they were asked for a bribe in six routine dealings with the state, covering utility connections, permits, licences and taxes. Because firms may not disclose bribery, the estimates are likely to be a lower bound.
Perceptions of public-sector corruption
Transparency International's Corruption Perceptions Index combines 13 independent data sources into a score from 0 (highly corrupt) to 100 (very clean) for 182 countries and territories. It measures how corrupt the public sector is perceived to be, not how often corruption actually occurs.
Illicit financial flows
SDG indicator 16.4.1 aims to measure money that crosses borders illegally, for example through trade misinvoicing, tax abuse or the proceeds of crime and corruption. Measurement is still at an early stage: official estimates of crime-related flows exist for nine countries, and 23 countries have piloted estimates of tax and commercial flows.