The present study analyses wage income inequality in Bulgaria during the period 2010-2019, using data from the National Revenue Agency (NRA) on the actual incurred income of taxpayers and survey data on wage income from the Household Budget Survey of the National Statistical Institute (NSI). Key indicators of income inequality are derived under both approaches, which are compared and evaluated through descriptive analysis. The NSI survey data permanently underestimates the level of income and inequality in its distribution, as evidenced by the Gini coefficient, the decile and percentile ratios, as well as other indicators based on them.