If you don’t have a 401k offered by your workplace, then an IRA is a no-brainer. You may even be eligible, if you have your own business, to contribute $55,000 (in 2018) to a SEP-IRA. But what if your workplace gives you a 401k? Should you contribute to an IRA on top of that? If so, what type should you choose – traditional or Roth?
First, you should understand that your limit is $5,000 ($6,000 if age >= 50). Since you have a 401k plan already, the limits and rules for an IRA on top of that are less generous. Now let’s first look at the IRS’s rules for contributions:
The key here is tax deductibility. If you stay below certain income limits, your traditional IRA contributions are deductible from your taxes, which is 90% of the benefit from these plans. However, tight income limits of $63,000 for singles and $101,000 for married filers makes this a difficult proposition. The worth of tax deductibility is based on your marginal tax bracket. The higher the bracket is, the more you save on taxes for the year with an IRA contribution. Based on 2018 tax brackets, at those incomes limits, the corresponding tax bracket is 24%. That’s quite low by historic standards. The general rule about Roth vs traditional 401k is that if your tax bracket is low now, you should choose Roth, for which you pay taxes now and everything accumulates tax free within the account. However, if your tax bracket is high now, you may benefit from deferring taxes, taking the savings up front, and withdrawing in retirement at a lower bracket. That’s the traditional IRA plan.
So basically, the conclusion is that if your income is such that you qualify for an IRA while you already have a 401k, your bracket is by default so low that you should only consider the Roth option. Now a wrench in this general guideline is state income tax. If you are in a high state income tax state such as Hawaii, California, Oregon, and Minnesota, be aware that Roth contributions mean paying all taxes up front, including state income taxes. These are the only corner cases where a traditional IRA is still worth considering even with a low federal tax bracket.
Regardless of what you do with the IRA, make sure you maximize the company sponsored 401k first, and put away enough in savings to meet emergency needs.