Capital expenditure mapping illustrates a country’s spending on capital projects. It provides a narrow slice of yearly of capital spending within a larger capital plan. Capital spending is could be viewed as facility project with specific amount within one fiscal year. In Nigeria, the drivers for capital spending include: regulatory mandates; breakage/emergency repair; level of service targets; plans and studies; asset condition; scheduled maintenance; public interest and availability of FGN-retained revenue. It is one way for policy makers and community members to better understand the distribution of funding and the delivery of services. Capital expenditure mapping therefore, tracks the flow of money for the current fiscal year; however, the money does not describe the level of services provided or needed within an area.

Mapping assist in incessant review of budgetary programmes, projects and procedures of implementation in order to assess compliance with stated rules, assess service delivery, and identify difficulties and challenges. It is based on the collection, collation, and analysis of data on implementation activities. It focuses on the use of financial resources released to MDAs and whether they are expended in accordance with Appropriation Act. The emphasis of mapping could also be on the cardinal parameters of value for money, such as economy, efficiency and effectiveness.

Since the resumption of democratic governance in 1999, the implementation of budget particularly the capital expenditure has been controversial. The implementation process has been well-laid out but not diligently followed, thus, occasionally ending--up with blames and counter-accusations between the executive and the legislature. Overall, mapping will assist the legislature in its oversight functions. The National Assembly monitors budget performance through its oversight activities on MDAs. The role of the legislature in the management of public funds does not end with the passage of the
Appropriation Bill into an Act. Sections 88 and 89 of the 1999 Constitution (as amended) empower the National Assembly to oversee the budget execution and implementation.