Roth IRA vs. 401(k): What's the Difference?

How a 401(k) works

A 401(k) is a retirement plan sponsored by an employer, funded through payroll deduction. A traditional 401(k) is funded with pre-tax contributions, reducing current taxable income, with withdrawals taxed in retirement. A Roth 401(k), where offered by an employer's plan, is funded with after-tax contributions, with qualified withdrawals in retirement tax-free.

How a Roth IRA works

A Roth IRA is opened individually, outside of an employer, and funded with after-tax dollars. Qualified withdrawals of both contributions and earnings in retirement are tax-free, provided IRS holding-period and age requirements are met.

Tax treatment differences

Traditional 401(k) and traditional IRA contributions are generally made pre-tax, lowering taxable income in the contribution year, with withdrawals taxed as ordinary income in retirement. Roth 401(k) and Roth IRA contributions are made with after-tax dollars, with no upfront tax reduction, but qualified withdrawals are tax-free.

Income and contribution limits

Roth IRA eligibility phases out above income thresholds set annually by the IRS, based on filing status. 401(k) plans, whether traditional or Roth, have no income limit restricting an employee's ability to contribute. Contribution limits for 401(k)s and IRAs are set separately by the IRS, with each account type having its own annual cap.

Contributing to both

There is no rule preventing an individual from contributing to both a 401(k) and a Roth IRA in the same year, subject to each account's own contribution limit and, for the Roth IRA, its income eligibility limit.

Portability when changing employers

A 401(k) balance is generally portable when leaving an employer — common options include leaving the funds in the former employer's plan (if permitted), rolling the balance into a new employer's 401(k), or rolling it into an IRA. A Roth IRA, by contrast, is not tied to any employer to begin with, so it is unaffected by a job change, since it was never linked to employment in the first place.

Early withdrawal rules

Withdrawing from a traditional 401(k) or traditional IRA before the age set by federal law generally triggers both ordinary income tax and an additional early-withdrawal penalty, subject to specific IRS-defined exceptions. A Roth IRA allows withdrawal of contributions (though not earnings) at any time without tax or penalty, since contributions were already made with after-tax dollars — a structural difference from how early withdrawals are treated on the traditional, pre-tax side of either account type.

401(k) loans

Some 401(k) plans allow the account holder to borrow against the vested balance, subject to IRS-set limits on the loan amount and a required repayment schedule, typically through payroll deduction. This loan feature is not available on an IRA, whether traditional or Roth — IRA rules do not include a loan provision, so accessing IRA funds early falls under the standard early-withdrawal rules instead.

Investment options within each account type

A 401(k) plan's investment menu is selected by the employer or plan administrator, typically offering a curated list of mutual funds or target-date funds rather than the full range of the market. A Roth IRA opened through a brokerage generally provides access to a much broader universe of investment choices, including individual stocks, ETFs, and mutual funds, since it is not constrained by an employer-selected plan menu.

The backdoor Roth conversion process

Because Roth IRA eligibility phases out above certain income levels, some higher-income individuals use a two-step process sometimes described as a 'backdoor' Roth: making a nondeductible contribution to a traditional IRA, then converting that balance to a Roth IRA, which is not itself subject to the same income limit as a direct Roth contribution. This conversion process has its own tax reporting requirements and considerations under IRS rules, particularly when the individual holds other pre-tax IRA balances at the time of conversion.

Frequently Asked Questions