Income reporting for 2018 and lump sum

[hodge]

I retired in May of 2018, with that, my sources of income was/is SS, former employer, and a rollover of pension to my 401k (also from my former employer). The rollover was viewed as a Lump Sum and I paid 20% tax upon the rollover. What I am confused about is how do I determine what bracket I would fall into, and what is my estimated income as viewed by IRS? I'm needing to make a withdrawal from the 401k to cover a purchase of a car and have a minimal effect on total income for 2018. My concern is where this places me with respect to tax bracket, and whether or not I've over or underpaid taxes (so far). I've tried to estimate all this using (apparently outdated IRS forms, since they aren't available, yet). The form is massively confusing but I spent hours trying to figure it out and am not confident that I did it right. Does anyone have any suggestions?

[Carl]

The provided phone number is a SCAM. It is not a valid TurboTax number. Anyone at that number claiming to be from TurboTax is a LIAR. Do not call it or give them any of your personal information.

[hodge]

What are you talking about? I have no number at all in my post.