If you have access to both a 401(k) and a Roth IRA, deciding which to fund first can feel like a tax puzzle, but a simple order of operations answers it for most people. The key difference is timing: a traditional 401(k) usually gives you a tax break now and taxes withdrawals later, while a Roth IRA is funded with after-tax money and grows and withdraws tax-free in retirement. Your current tax rate, your expected future rate, and your employer's match all shape the right order.

Step one is almost always the same: contribute enough to your 401(k) to capture the full employer match, if one is offered. A typical match, such as 50 percent of the first 6 percent you contribute, is an instant return no investment can reliably beat, and leaving it unclaimed is leaving salary on the table. If your employer offers no match, this step does not apply, and you can move straight to the next one.

Step two is usually a Roth IRA, for two reasons. First, Roth IRAs offer flexibility that 401(k) plans do not: you can withdraw your contributions, though not the earnings, at any time without penalty, which makes the account useful as a secondary safety net. Second, Roth IRAs typically offer a much wider investment menu than an employer plan, including low-cost broad index funds, without the administrative fees some 401(k) plans charge.

Step three is to return to the 401(k) and increase contributions beyond the match, up to the annual limit, once the Roth IRA is funded. This makes sense because the 401(k) still offers valuable tax deferral and a much higher contribution limit than an IRA. People aiming for financial independence often fill both accounts, since the combined room lets them save a large share of income in tax-advantaged accounts each year.

There are exceptions to this order. If you are in a very high tax bracket now and expect a much lower one in retirement, maximizing pre-tax 401(k) contributions first can make sense. If your 401(k) has unusually high fees or poor investment options, favoring the Roth IRA more heavily is reasonable. And if you are self-employed or your employer offers a Roth 401(k) option, the same logic applies with the tax treatment flipped: Roth contributions cost tax now and save it later.

A common mistake is treating the choice as permanent. You can adjust your split every year as your income, tax situation, or employer plan changes. The important thing is to be saving in tax-advantaged accounts at all, and to automate the contributions so they happen before you have a chance to spend the money. A good plan you actually follow beats a perfect plan you keep postponing.

To put this into action, check your employer match today, set your 401(k) contribution to at least the match level, open a Roth IRA if you do not have one, and automate a monthly contribution to it. Once both are running, revisit the split once a year, ideally when you get a raise, and direct part of each raise to the account that is furthest from its annual limit.

An additional consideration is the effect of each account type on your tax picture in retirement, since having both pre-tax and Roth money gives you flexibility to manage your taxable income year by year. In retirement, you can draw from pre-tax accounts up to a low tax bracket and top up spending from Roth money tax-free, which can keep your overall tax bill lower than drawing from a single account type. This diversification of tax treatment is sometimes called tax diversification, and it is a strong argument for funding both account types over a career rather than maximizing only one. Contribution limits and eligibility rules change periodically, so check the current limits each year before finalizing your split, and remember that employer plans may also offer after-tax contributions or Roth options that change the optimal order for your situation.