1. Mr. B gets a six month extension to file his 2016 return. The extension allows Mr. B to file his 2016 return on or before October 15, 2017. Mr. B mails his return on October 10, 2017. The post office postmarks the envelope containing the return October 11, 2017. The IRS receives the return on October 14, 2017. The IRS issues a SND for Mr. Bs 2016 year on April 6, 2019. Mr. B does not file a Tax Court petition. When does the SOL on assessment expire? Assume 3 year SOL. (Please, explain)

2. Same facts as in Question 1, except the IRS received the return on October 17, 2017. (Please, explain)

3. Same facts as in Question 1, except Mr. Bs correct gross income was $200,000. On his return he reported $150,000. Furthermore, Mr. B did not make any disclosures with respect to his gross income. (Please, explain)