The amount in box 2a of the code JP 2019 Form 1099-R must be included on your 2018 tax return. If that amount was not included on line 4b of your 2018 Form 1040, you must amend your 2018 tax return. You would do this using 2018 TurboTax by entering the code JP 2019 Form 1099-R and in the follow-up indicating that it is a 2019 Form 1099-R.
If the code JP 2019 Form 1099-R does not show any amount of tax withholding, there is no need to enter it into 2019 TurboTax. If you do enter it, 2019 TurboTax will ignore it other than to remind you over what I said in the paragraph above.
