During the month of April most years, the federal government runs a surplus as many people pay their taxes in that month. Other times of the year there are sometimes surpluses, especially after quarterly tax payments are made.
Data Source: U.S. Department of the Treasury. Fiscal Service, Federal Surplus or Deficit [-] [MTSDS133FMS], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/MTSDS133FMS, April 8, 2017.
Data Source: NYS Assembly Yellow Book, page 11. http://assembly.state.ny.us/Reports/WAM/2017yellow/files/2017yellowbook.pdf