Beginning with tax year 2015, the Department of Taxation and Finance (hereafter “the Department”) began producing a new annual population data study file to provide more comprehensive statistical information on New York State personal income tax returns. The data are from full‐year resident, nonresident, and part‐year resident returns filed between January 1 and December 31 of the year after the start of the liability period (hereafter referred to as the “processing year”). The four datasets display major income tax components by tax year. This includes the distribution of New York adjusted gross income and tax liability by county or place of residence, as well as the value of deductions, exemptions, taxable income and tax before credits by size of income. In addition, three of the four datasets include all the components of income, the components of deductions, and the addition/subtraction modifications. Caution: The current datasets are based on population data. For tax years prior to 2015, data were based on sample data. Data customers are advised to use caution when drawing conclusions comparing data for tax years prior to 2015 and subsequent tax years. Further details are included in the Overview.