I assume that you received monthly payments, some before and some after your birthday.
"Splitting" a 1099-R is a situation that TurboTax does not support so you must do it yourself.
Figure out how much pension was received before and after your birthday and enter those amounts on two separate CSA-1099-R entries, with all boxes the same but the amounts adjusted for before-and-after birthday so the two total the original.
Then the before birthday amounts will go on line 1 on the 1040 as wages and the after will go on line 4 as pension as you enter each one and answer the age question as before the age and after the age.
The fact that you entered it as two 1099-R's does not go on your tax return, only the total values do, so as long as they add up to the same amounts as on the original CSA-1099-R it makes no difference.
Be sure to choose the CSA 1099-R type and not just a 1099-R since the boxes are different.
BTW: this will only make a difference if you qualify for some credit based on the amount of earned income which is the reason that before amounts are reported as wages since disability pay is a wage replacement until retirement age is reached.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
