(a) A cooperative audit is an audit in which two or more audit institutions (SAIs) are involved. The number of cooperative audits has become more prevalent in recent years for a number of reasons. Firstly, the economies of the world have become more interdependent and challenges have become more international. Cross-country cooperation is more effective in areas such as tackling money laundering, international crime or environmental issues, where working together can find a common solution.
Cooperative audits are practical for programmes of donor funds which apply to a number of countries, for example, the audit of donor funds to countries hit by a natural disaster such as a tsunami or earthquake. Donors require accountability and verification that their donations are being put to proper use.
Cooperative audits allow SAIs to learn from each other and in doing so improve their own best practices via shared knowledge and information. This reflects the INTOSAI motto which is that ‘mutual experience benefits all.’ Knowledge gained in cooperative audits can help SAIs to eliminate systematic errors in their own practices. In addition, cooperative audits can be a way of passing expertise, one SAI to another. For example, the SAI of one country may have experience in a particular area in which another country’s SAI has no experience.

(b) The three types of cooperative audit are a parallel (or concurrent) audit, a joint audit and a coordinated audit. GUID 9000 Cooperative Audits between SAIs provides the following explanations of each type of cooperative audit.
Parallel/concurrent audit
The audit is conducted more or less simultaneously by two or more autonomous auditing bodies, but with a separate audit team from each body, usually reporting only to its own governing body and only on matters within its own mandate.
A decision is taken to carry out similar audits. Methodology and audit approach could be shared.
Joint audit
The audit is conducted by one audit team composed of auditors from two or more autonomous auditing bodies who usually prepare a single joint audit report for presentation to each respective governing body. Key decisions are shared.
Coordinated audit
A coordinated audit is either a joint audit with separate audit reports to the supreme audit institutions’ own governing bodies or a parallel audit with a single audit report in addition to the separate national reports.

(c) Difficulties
The success of a cooperative audit is dependent on the commitment of all the SAIs involved. The Nigeria Audit Service may be committed to the cooperative audit but the SAIs from all the countries involved must have a sincere desire to cooperate with one another. Tasks need to be coordinated in common, fieldwork is to be conducted, reports need to be drafted and decisions need to be taken. If the SAIs cannot agree in these areas, a coordinated audit will be difficult to perform, regardless of the efforts of the Nigeria Audit Service. To combat this issue, the Nigeria Audit Service could suggest that the SAIs participating in the cooperative audit form a coordination committee or choose one SAI to act as the Coordinator SAI.
Sometimes a cooperative audit might be difficult due to legal barriers in a SAI’s country. If a legal barrier exists in one of the other countries taking part in the cooperative audit, this could prevent the cooperative audit taking place. Legal barriers can prevent joint audits where there is no legal authority for doing work outside the national territory.
Sharing of information between SAIs may be limited by legislation in some countries. If such legislation exists in one of the countries participating in the cooperative audit of the donor funds, this could make an effective cooperative audit difficult.
The cooperative audit is being performed across six different countries, each of which might have their own language (or languages). It will be difficult for SAIs to cooperate if there is a significant language barrier which will ultimately impact the quality of the cooperative audit.