Alison accidentally omitted $40,000 of gross income from the restaurant she owned on her 2012 tax return.

Question:

Alison accidentally omitted $40,000 of gross income from the restaurant she owned on her 2012 tax return. The return indicated gross income of $150,000 when it was filed on October 15, 2013. As of what date can the IRS no longer pursue Alison with the threat of collection of the related tax, interest, and penalties?