We are dealing with a 2016 Form 1040, individual income tax return, with an original due date of 4/15/2017. What is the latest date the taxpayer can file a claim for refund that will result in a refund under following circumstances? Note that the word "filed" below means "filed" as used in the Code; it does not mean "mailed." Dates do not fall on a Saturday, Sunday, or holiday unless otherwise stated. New Facts: We are still dealing with a 2016 Form 1040, individual income tax return. Client filed the return on the original due date of 4/15/2017. The tax originally shown on the return was $100,000. Client paid: * - $50,000 on March 30, 2017 * - $30,000 on September 30, 2018 * - $20,000 on July 31, 2019 Client later determined the liability should have been $0. 

How much should IRS refund if Client files a claim for refund on the following dates? Client filed claim for refund on 10/1/2019?