Calculate the 10 percent penalty for the early 401K withdrawal on Form 5329.[1] This amount will be transferred to line 59 on Form 1040.Report your 401k distribution amount from your Form 1099-R on your Form 1040. Withdrawals from a 401(k) go on line 16a. If the entire amount is taxable, which is typically the case, enter the total amount on line 16b, too.Related How to File Taxes With 401(k) DistributionsFootnotes[1] https://www.irs.gov/pub/irs-pdf/...