1) I did (started) a backdoor Roth IRA (contributed to tradition IRA and converted to Roth IRA) and for years 2023 and 2024 in March of 2024. Now, I have received 1099-R for year 2024 with early distribution of $13,500.
On TURBOTAX, Under "deduction & credits" I did make the IRA contribution ($7000) non-deductible for year 2024. But how and where shall I report the after tax non-deductible contributions for 2023 for balancing out the reported early distribution of (6500 +7000 = 13500) on 1099-R ?
2) I am filing my taxes jointly with my spouse. I filled "retirement and investments section" under "deduction & credits" for year 2023 correctly.
You can enter your prior year basis, from your 2023 Form 8606 line 14, either during the IRA contribution interview (steps 8 & 9) or in the retirement section (steps 8 & 7). You should get the question "Any nondeductible Contributions to your IRA?" If you do not get the question then please see Why am I unable to report my 2023 for 8606 basis?
To enter the nondeductible contribution to the traditional IRA:
To enter the Form 1099-R conversion:
"But how and where shall I report the after tax non-deductible contributions for 2023"
That was reportable on your 2023 tax return on 2023 Form 8606. The 2023 Form 8606 will have $6,500 on line 14 which transfers to line 2 of your 2024 Form 8606.
If your 2023 tax return failed to include the 2023 Form 8606, you'll need to amend.