When I ERed back in 2008, I had to liquidate my 401k because it had company stock in it and I wanted to cash it out using NUA. I received two 1099-R forms (one for the company stock and one for everything else) and had to combine some numbers from them before entering the sum on my 1040 form. I did my taxes by hand, not using any tax software.
Retired in late 2008 at age 45. Cashed in company stock, bought a lot of shares in a big bond fund and am living nicely off its dividends. IRA, SS, and a pension await me at age 60 and later. No kids, no debts.
"I want my money working for me instead of me working for my money!"