This paper investigates the macroeconomic determinants of Romania’s budget deficit over the post-EU accession period, drawing on quarterly data from Q1 2007 to Q2 2025. Using an Autoregressive Distributed Lag (ARDL) model, we identify both short- and long-run relationships between the fiscal balance and a set of macroeconomic fundamentals. Real GDP growth proves to be the most robust positive determinant, with a short-run coefficient of 0.2718 and a long-run multiplier of 0.5152—a finding that firmly establishes sustained economic expansion as the primary structural force behind fiscal improvement. […]