It's doubtful that the difference has anything to do with a software update.
There's a good chance that the lower taxable amount was the result of using the Simplified Method to calculate the taxable amount of periodic pension distributions. Use of the Simplified Method requires that the pension was partially paid for with after-tax investment in the plan. Pension payments are then a mix of this after-tax basis and taxable amounts with the basis paid out at a rate based on life expectancy.
Generally a payer will calculate the taxable amount and include it in box 2a. However, if the payer does not know the correct taxable amount, they'll leave box 2a blank and mark box 2b taxable amount not determined. one would only use the Simplified Method in TurboTax if the taxable amount in box 2a was either wrong or not provided. Getting a correct taxable amount using the Simplified Method in TurboTax requires providing specific details that are easy to get wrong. Also, many people make the mistake of thinking that since TurboTax offers to calculate the taxable amount of periodic payments that they should even though a proper taxable amount has been provided in box 2a.
A taxable amount of far less than the gross amount seems to suggest that the Simplified Method was used improperly to do the calculation. If the gross amount came from a single Form 1099-R, this is likely what happened.
It would be helpful to compare to the 2018 tax return. On that tax return the corresponding lines would be Form 1040 lines 4a and 4b, but that form combines IRA and pensions onto a single pair of lines instead of using separate lines for IRAs and pensions. To compare to 2019 tax return you would have to add line 4a to 4c and line 4b to 4d of the 2019 Form 1040.
Does the Form 1099-R have a blank box 2a and box 2b Taxable amount not determined marked?
