If this occurred in 2024 then you should have received a Form 1099-R. On the 1099-R any federal income taxes withheld will be entered in box 4 of the form. The taxes withheld flow to the 2024 federal tax return, Form 1040 Line 25b.
To enter, edit or delete a form 1099-R -
Click on Federal Taxes (Personal using Home and Business)
Click on Wages and Income (Personal Income using Home and Business)
Click on I'll choose what I work on (if shown)
Scroll down to Retirement Plans and Social Security
On IRA, 401(k), Pension Plan Withdrawals (1099-R), click the start or update button
Or enter 1099-r in the Search box located in the upper right of the program screen. Click on Jump to 1099-R
Online editions -
On the screen Did you get a 1099-R in 2024? Click on Yes
On the screen Let's import your tax info Click on Change how I enter my form
On the screen How do you want to add your 1099‑R? Click on Type it in myself
On the screen Who gave you a 1099-R? select the type of 1099-R you received and Continue
What does 2023 have to do with it? If you converted to a ROTH IRA in 2024 you should have a 1099R for it. The tax withholding is in box 4. Or what/how did you pay the 2023 tax at the beginning of 2924?
Enter a 1099R under
Federal Taxes
Wages & Income
Then scroll way down to Retirement Plans and Social Security
Then IRA, 401(k), Pension Plan Withdrawals (1099-R) – Click Start