End-May, the budget gap stood at RON7.42 billion, or 1.36% of GDP.
The first-half figures were below the RON12.6 billion deficit target agreed with the International Monetary Fund, the data showed.
Total revenue to the consolidated budget rose 9.6% on the year to RON85 billion at the end of June, while overall expenditure was up 0.7% to RON96.2 billion.
Romania pledged to lower the budget deficit to 4.4% of GDP in 2011, from 6.5% of GDP a year earlier.