You'll enter the Form 1099-R reporting this distribution. Enter the Form 1099-R under Wages & Income -> Retirement Plans and Social Security -> IRA, 401(k), Pension Plan Withdrawals (1099-R).
The Form 1099-R will have the gross distribution in box 1, the taxable amount in box 2a, tax withholding in box 4, any after-tax basis included in the distribution in box 6, the NUA amount in box 6, and code 1, 2 or 7 in box 7 (depending on your age at distribution and your age at separation from service). The taxable amount in box 2a will be the amount in box 1 minus the amounts in boxes 5 and 6 (but not less than zero).
Be sure to keep track of the NUA amount and the basis in the NUA shares for use when you eventually sell the shares since the brokerage might not retain that information.
