If I contribute to a 401K before April 15th 2024, will I be able to count that as a deduction from my gross total 2023 income? and how to report it?

[Anonymous]

We already have a W-2, so how could I count a 401K contribution on 2023 taxes?

[DoninGA]

Contributions to an employer provided 401(k) account can only be made during the tax year, so 12/31/2023 was the last date that you could contribute.

Your W-2 has Box 12 coded with a D and the amount of contributions you made in 2023 to the 401(k).  Those contributions are not entered anywhere else on a tax return.

[VolvoGirl]

How would you make a new 401K contribution?  They have to be deducted from your paychecks.    It is too late to increase your deduction for 2023.  Anything deducted in 2024 will go on your 2024 W2 next year. 

And if you can write a check to the 401K it would be non deductible and not pretax.  And isn't reported on your tax return.  The plan would keep track of it and when you take a distribution part of it will come out tax free,

[Opus 17]

Workplace plans like a 401k or 403b, are covered by different sections of the tax law and have some completely different rules than IRAs, and should not be confused with each other.