Did you take an actual distribution or did you take out a
loan.?
If you took out a loan, it would not be taxable income
until it is declared to be in default.
If you took an actual distribution, you should request a
1099-R from your 401(k) administrator.to be entered in the following area:
Type in 1099-r in the search box,
top right of your screen, then click the magnifying glass
Click the jump to 1099-r link
in the search results
Follow to prompts and online instructions