Kevin deliberately omitted $40,000 of gross income from his restaurant on his 2016 tax return. The return

Question:

Kevin deliberately omitted $40,000 of gross income from his restaurant on his 2016 tax return. The return indicated gross income of $200,000 when filed on April 14, 2017. When can the IRS no longer pursue Kevin with the threat of collection of the related tax, interest, and penalties?