This study examined the relationship between fiscal management and fiscal deficit in Nigeria. An ex-post facto research design was adopted, using annual time-series data obtained from the Central Bank of Nigeria’s Statistical Bulletin covering the period 1990–2024. Fiscal deficit was modelled as a function of government expenditure, government revenue, government expenditure-to-GDP ratio and government revenue-to-GDP ratio. The Augmented Dickey-Fuller test was employed to establish the stationarity of the variables, while the Johansen co-integration test was used to determine the existence of a long-run relationship. An Error Correction Model was subsequently estimated to examine the short-run dynamics and adjustment towards long-run equilibrium. The findings established that the variables were integrated of order one and that a long-run relationship exists between fiscal deficit and the selected fiscal management indicators. The Error Correction Model further revealed that government expenditure, government expenditure-to-GDP and government revenue significantly influence fiscal deficit at different lags, while government revenue-to-GDP has a delayed effect on fiscal deficit. The significant error correction mechanism further confirms adjustment towards long-run equilibrium following short-run disturbances. The study concludes that fiscal deficit in Nigeria is strongly influenced by the effectiveness of revenue mobilisation and expenditure management. It therefore recommends an integrated fiscal management framework that strengthens domestic revenue mobilisation while ensuring disciplined, efficient and sustainable public expenditure.

Keywords: Fiscal management; fiscal deficit; government revenue; government expenditure; fiscal sustainability; Nigeria.