I started a new employer in December of 2021 and they took out 401k contributions for my first paycheck (which included a sign-on bonus, so the 401k contribution is pretty hefty) (dated last day of the month/year, received first bank day of the year). I had informed them I had already reached the limit, but I guess that didn't make it into their payroll system.
I didn't notice this at the time since it was received in the beginning of the year I assumed it was withheld for 2022, and I didn't check my W2 until I was doing taxes this weekend (I know, I should have done it earlier...), but it seems like its too late to get it corrected before the deadline on Monday (or might have already passed?)
It seems like my best course of action is report it as excess deferral so it gets taxed properly for 2021 and then just let it ride until I retire. Getting it backed out at this point means I pay taxes on it now (while I'm a high bracket earner) and I get a 10% penalty.
For what it's worth Turbo tax 'completechecker' or whatever its called doesn't catch my contribution overage.
