The reporting that they have provided on these Forms 1099-R implies that they have not themselves done the calculation of taxable gains, instead apparently relying on the participant to do the calculation. If they marked box 2b Taxable amount not determined to indicate this they should have left box 2a blank per the IRS instructions for Form 1099-R. If they actually did do the calculation of taxable gains to be able to distribute the appropriate amount, they are required to show the taxable gains in box 2a and not mark box 2b Taxable amount not determined.
