Answering that it's a periodic payment when it's not causes TurboTax to go into the questions regarding the Simplified Method or the General Rule, neither of which apply to a nonperiodic payment, and those questions are confusing enough that many people provide inaccurate information and end up causing the taxable amount to be underreported, which the IRS Automated UnderReporter system catches and results in the taxpayer receiving CP 2000 and a tax bill. The calculation using the Simplified Method or the entry for the General Rule overrides the taxable amount show in box 2a of the Form 1099-R. The taxpayer then posts on this forum asking why "TurboTax" underreported their income.
