Anticipating your next question, Box 7 has code 8 which is for an excess contribution. The letter from the 401k plan and everything I have read says that the excess contribution needs to be reported in the tax year it was received, not the tax year the original contributions were made. So in my case, I got the check in 2021 from the 401k plan so I need to report that as taxable income for 2021.
