It's one month before the 2015 tax filing deadline. I didn't contribute as much as I could have into my 401k in 2015 (I only contributed $8k instead of $18k), but would like to realize as much tax advantage as possible on my 2015 taxes. I've already increased my contributions to ensure I contribute the max ($18k) in calendar year 2016, but would appreciate any input on how to maximize my tax savings on my 2015 filing.

I've contributed $2k to my 401k in calendar year 2016. Is it possibly to allocate or earmark the $2k I've contributed in calendar year 2016 to tax year 2015?

Comparable to an IRA, is it possible to make a retroactive contribution for the previous tax year before the tax filing deadline in the current year?


1 Answer 1


No, you cannot. 401(k) contributions are allocated to the year in which contributed. This is unlike IRA, where you can contribute until the tax day.

  • Solo 401k are an exception to this.
    – BrenBarn
    Mar 17, 2016 at 1:38
  • Not exactly... The reason it works for solo 401k is because the plan owners are allowed to submit contributions until the April 15th, and in case of solo 401k the owner happens to also be the contributor.
    – littleadv
    Mar 17, 2016 at 3:28
  • Yes, but the effect is that you can contribute to your own Solo 401k until the tax filing deadline.
    – BrenBarn
    Mar 17, 2016 at 3:45
  • According to this Huffington Post article, it is possible to earmark 2016 401k contributions for tax year 2015.huffingtonpost.com/wiseradvisorcom/… Do you think this was a mistake on their part and they confused 401k with IRA? Mar 17, 2016 at 15:50
  • @Hanoihancock not unless you're self employed.
    – littleadv
    Mar 17, 2016 at 20:31

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