The total amount of my pension annuity payments is not filling in correctly from the Step by Step amount. The amount of taxable income on Form 1040 line (b) but my rollover amount was about $26,000 higher than the difference between line 4(a) and 4(b). I had just one rollover.
Due to the combination of lines 15 & 16 from the 2017 return to one single line 4 on the new 1040 the amount on 4a may not look correct even though it is ... so if 4b is correct then do not worry about 4a making sense.
They are redesigning line 4 for the 2019 return to fix this confusing situation.
Critter is correct. The change last year caused massive amounts of confusion, but TurboTax is correctly completing line 4 according to the (confused) IRS instructions.
The problem stems from rollovers. According to the IRS instructions (see page 28 and following at https://www.irs.gov/pub/irs-pdf/i1040gi.pdf), you enter some distribution amounts in 4a and you don't enter others, even though you enter all taxable distributions in 4b. This instruction can make 4b, the taxable amount, larger than 4a (which is supposedly the total amount of distributions).
As Critter says, don't worry about it. TurboTax is doing it according to the IRS instructions, and the IRS is only going to worry about 4b anyway.