I cashed out a 401k last year. How do I report that?

[SteamTrain]

You should have...or should soon get (in the next couple weeks) a 1099-R for that distribution.

You'll enter that 1099-R on the Wages&Income page, down in the retirement income section.  IF you rolled the $$ into an IRA within 60 days of the distribution, you'll have followup questions, after the main form entry, where you indicate that.  IF you didn't, then it's all taxable, and subject to a 10% penalty if you were under age 59.5. 

 Any tax  withholding done will be shown on the 1099-R form, and is entered with the main software form, but it might only partially cover what taxes you owe on teh distribution....depends on what other income you had alll year.