Assume current date is 2/20/2020 Oscar, your client, wants to file his 2019 return, with total gross income of $50,000 Assume Oscar filed a timely extension and filed his 2019 return on 6/30/2020 Oscar comes back to you in 2021 and said he forgot to report $100 of interest income. Until what date does Oscar have to go back and amend his 2019 tax return? 10/15/2020 6/30/2023 4/15/2023 6/30/2026