; and (B) private sector bug bounty programs, including such programs implemented by leading technology companies in the United States; and (2) recommendations on the feasibility of initiating bug bounty programs at appropriate agencies and departments of the United States. IV Voting system integrity audit 401. Audit (a) In general Not later than December 31, 2019, and once every 4 years thereafter, the Comptroller General of the United States shall conduct a robust audit of State voting systems to ensure that elections held using equipment upgraded using grants awarded under section 203 have been conducted in a manner consistent with the goals of the grant program. (b) Limitation Each audit conducted under subsection (a) shall include only States that received a grant under section 203 during the time period covered by the audit. (c) Report The Comptroller General of the United States shall submit a report to Congress on each audit conducted under subsection (a).