Actually, I overcontributed 6K in 401K and 3K in 401K Roth. My 401K administrator told me that I won't receive the tax statements in 2021 and will receive them in Feb-2022. So I proactively reported the excess 6K in 2021 while filing my 2020 tax returns. Also, I have been told to skip the excess 3K (401k Roth) reporting which I already paid tax. thank you!
