The World Bank has said about 80 per cent of businesses in Nigeria bribe government officials.
In its 2011 investment assessment of Nigeria, the global bank said: “One-third of micro-enterprises reported that informal payments/gifts to government officials were commonplace, suggesting that registered firms confront more requests for such bribes.” It added: “Only 20 per cent of microenterprise firms reported having advance knowledge of the amount of the payment required to ‘get things done’.” 
Such uncertainty, the report stated,  “adds to the challenge posed by informal payments, since the amount to be set aside cannot even be planned for. Informal payments/gifts represented approximately 1.2 per cent of annual sales for all micro-enterprises”.
It stated that “micro-enterprises dealing in government contracts are expected to pay approximately 4.3 per cent of the contract value in order to secure it. The bribes required to obtain contracts appear much smaller for services (3.9 per cent) than for manufactured goods (6.7 per cent),” the report said.
However,“formal sector firms pay more for corruption: 47 per cent of formal firms claimed that informal gifts/payments were commonplace, compared to 33 per cent of microenterprises.
The report added that micro-enterprises have a greater mistrust of institutions than formal firms. Indeed, 63 per cent of formal sector firms reported that the application of laws was not consistent and predictable, compared to 72 per cent of microenterprises, it said. 
In addition, 41 per cent of formal firms reported that they had advanced knowledge of informal payments/gifts, compared to 20 per cent of microenterprises. 
As for the costs,informal payments/gifts represented 3.2 per cent of annual sales and the cost of securing a government contract reached approximately 8.4 per cent of its total value for formal firms; these proportions were much lower, 1.2 per cent and 4.3 per  cent, for microenterprises.
The report studied business activities and investments in 26 states, namely: Adamawa, Akwa Ibom, Bayelsa, Benue, Borno, Delta and  Ebonyi. 
Others are Edo, Ekiti, Gombe, Imo, Jigawa, Katsina, Kebbi, Kogi, Kwara, Nasarawa, Niger, Ondo, Osun, Oyo, Plateau, Rivers, Taraba, Yobe and Zamfara.