Farm gate nitrogen (N) balance and use efficiency was estimated across 150 specialist Irish dairy farms over a 7 year period between 2006 and 2012 using nationally representative data. The study period coincided with the introduction of EU Nitrates Directive regulations aimed at minimising losses of N to the aquatic environment and results indicated that N balance declined by 25.1 kg ha−1 from 180.4 to 155.3 kg ha−1 over the study period. This decline can almost entirely be attributed to reduced chemical N fertiliser inputs of 23.1 kg ha−1 over the period, equivalent to 1247 kg N, or a cost saving of €1347 per annum across the average dairy farm. Nitrogen use efficiency also increased by 2.1 % points over the period from 20.8 to 22.9 %. This was achieved while increasing milk solids output from 405.3 to 449.6 kg ha−1 in the context of a declining stocking rate (1.86–1.84 livestock units ha−1). These results suggest some positive impact of the regulations on N management on Irish dairy farms at the nutrient source end of the nutrient transfer continuum. This increased N management efficiency has a potential double dividend effect of increased returns to agricultural production while reducing the risk of N transfer to the aquatic environment. In addition to the introduction of the regulations, results of a random effects panel data model indicated that N balance and use efficiency are significantly influenced by factors such as fertiliser prices, stocking rates, land use potential, contact with extension services and climatic variables.