In the case that your annual income is right in the limit between one tax bracket and the next tax bracket, can contributing to a 401k or IRA reduce your present income declaration in such a way that your taxes fall into a smaller tax bracket?

Does it apply the same way between traditional and Roth 401Ks/IRAs?

p.s. Any references to the IRS or viable sources would be greatly appreciated.

  • Hi Peretz, welcome to Money.SE, good first question!
    – C. Ross
    Commented Nov 29, 2012 at 20:17
  • This tax table is from 2012 and it’s for a person filing single...is it still accurate for 2020?
    – melissam
    Commented Dec 28, 2020 at 2:55
  • The numbers have changed, updated every year, but the process, the concept of marginal rates, still applies. Just look at a current tax table for this year.. Commented Dec 28, 2020 at 19:22

3 Answers 3


From my friends at Fairmark this is the 2012 tax table.


This is the table of tax due on taxable income, i.e. the 'bottom line' of the return after all deductions, credits, etc.

If your taxable income is exactly $35,350, you are "in the 15% bracket" as the last $100 was taxed at 15%. But, the next $100 of income would be taxed at 25%.

Yes, part of the 401(k) process is that you need to be aware of what the tax would have been on the pre-tax 401(k) money. Since a Roth is post-tax money, it doesn't change your bracket, only pre-tax 401(k) or Traditional IRA will do that. At a taxable $50,000, you are clearly in the 25% bracket and would choose your account accordingly. You can see above, the way the tax structure works is progressive. i.e. The tax on $35,350 is fixed at $4867.50 and only the amount above this is taxed at 25%. The next $100 or $1000 in taxable income won't push other income into the higher bracket.

Many use the strategy user102008 alluded to, navigating one's retirement deposits so the pretax account saved them from 25% income, but doesn't drop too far into the 15% bracket. A mix of Traditional 401(k), Roth 401(k), Traditional IRA, and Roth IRA, can help you hit the goal dead-on if you are willing to pay a bit of attention during the year.

  • Yeah... Where's the AMT in that table?:)
    – littleadv
    Commented Dec 29, 2012 at 4:49
  • @littleadv - LOL good point, and why I like the idea of depositing the IRA funds right at tax time which lets you decide whether the Roth or Traditional is preferable. Commented Dec 29, 2012 at 5:09

Yes, if your income is right at the beginning of a tax bracket, deducting from the taxable income (which is what Traditional 401(k) and Traditional IRA do) may drop your income so it is in a lower tax bracket. Roth 401(k) and Roth IRA are post-tax, and they do not affect the taxable income at all, so that obviously doesn't apply to them.

But I really want to point out that "dropping your taxable income to a lower bracket" is not useful in and of itself. What I am trying to say is that, given that you will reduce your taxable income by a given amount, I don't see any benefit of it causing your income to go to a lower bracket, vs. dropping the same amount but staying in the same bracket.

In fact, one could argue that it may be even "worse" for it to drop to a lower bracket, because that means part of your 401(k)/IRA is deducting income that is taxed less, so it is saving less tax; whereas if you had deducted the same amount, but your income stayed in a higher tax bracket, then your entire 401(k)/IRA is deducting higher-taxed income.

(Note: I am not saying that it is not useful to use 401(k)/IRA to lower your taxable income below certain levels. For example, eligibility for many tax credits, deductions, exemption from AMT, and other tax benefits often have an income limit, and using a 401(k)/IRA to reduce your taxable income in order to get under these limits is a common and useful strategy. However, these income limits do not correspond to tax brackets. And since the question asked specifically about going to a lower tax bracket, I am just saying that only going to a lower tax bracket, specifically, is not useful.)

  • Also note that the IRA deduction will only appear when your taxes are filed. Your employer will not know about them, and will over withhold, unless you make an adjustment to your W4. The 401K contribution will be automatically be reflected in take home pay Commented Nov 25, 2012 at 14:03
  • @user102008: Quick question. Lets say that at 50k my tax bracket changes from 15% to 20%. Is the 20% only applicable to the exceeding amount (e.g. 5k from a 55k income declaration) or to the full amount (e.g. 55k). If the former is correct, I agree with your analysis. Otherwise it would be a viable option to invest your contributions in the traditional 401k/IRA to drop your bracket.
    – Peretz
    Commented Nov 25, 2012 at 14:28
  • 2
    Yes, higher tax bracket applies to the exceeding amount
    – Vitalik
    Commented Nov 25, 2012 at 15:29
  • Is it possible to use the traditional 401k, to drop my income below the Roth IRA limit? That way I can contribute initially to my traditional 401k and once I push my income below certain limit, I am allowed to save in my Roth IRA for the year.
    – Peretz
    Commented Nov 25, 2012 at 21:26
  • 2
    @Peretz: You can, and some people do this. However, (assuming you don't have an existing Traditional IRA) a much simpler and more robust way to circumvent the Roth IRA contribution income limit is to do a backdoor Roth IRA contribution, which works at any income.
    – user102008
    Commented Nov 26, 2012 at 3:33

My income is a bit over the phase-out for deducting traditional IRA contributions (see the tables on page 13 of Publication 590 - these may move around in future editions). This means that if I put all my 401k contributions into a Roth, then no IRA contributions will be deductable. I have some going to Roth and some going to traditional 401k so that I move my AGI down to where some of my traditional IRA contribution is deductable.

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