401(k) vs. Roth IRA: How the Accounts Actually Differ

A 401(k) is an employer-sponsored retirement plan. A Roth IRA is an individual retirement account funded with nondeductible contributions. These labels describe different dimensions: 401(k) versus IRA identifies the account structure, while traditional versus Roth identifies the federal income-tax treatment of contributions and qualified withdrawals.

A workplace plan can permit pre-tax 401(k) deferrals, designated Roth 401(k) contributions, or both. Someone asking whether to use a ‘401(k) or Roth’ may therefore be choosing among a traditional 401(k), Roth 401(k), traditional IRA, and Roth IRA—not merely two interchangeable accounts.

For 2026, the employee elective-deferral limit for a 401(k) is $24,500. Eligible participants may have additional catch-up contribution capacity. The combined 2026 contribution limit across a person’s traditional and Roth IRAs is $7,500, with a separate $1,100 IRA catch-up limit for eligible people age 50 or older.

Direct Roth IRA contributions are also subject to modified-adjusted-gross-income phaseouts. A designated Roth 401(k) contribution is not subject to those Roth IRA income limits, although the workplace plan must offer the feature and normal plan contribution rules still apply.

A 401(k) may include matching or other employer contributions under a plan-specific formula. Review the contribution rate required for the full match, the timing of deposits, true-up provisions, and the vesting schedule. Employee salary deferrals are always fully vested, while some employer contributions may vest over time.

A Roth IRA has no employer match. That does not make it inferior; it means the IRA should be evaluated on its own eligibility, investment access, costs, tax treatment, beneficiary rules, and flexibility after the workplace-plan match has been understood.

Traditional 401(k) elective deferrals generally reduce current taxable income and are generally taxed when distributed. Roth 401(k) and Roth IRA contributions are included in current income, while qualified distributions can be tax-free when the applicable requirements are met.

Paying tax now is not automatically better or worse than deferring it. The comparison depends on current and future marginal tax rates, the length of compounding, state taxes, withdrawal sequencing, and uncertainty. Using both tax treatments can diversify future tax exposure, but it does not guarantee a lower lifetime tax bill.

A 401(k) participant selects from the plan’s menu and may pay plan administration and investment expenses. A Roth IRA generally offers a wider menu at the chosen custodian, but investment availability, trading costs, advice fees, and cash-management rules still vary by provider.

Withdrawal and rollover rules are not identical. A Roth IRA distinguishes regular contributions, conversions, and earnings through ordering and qualification rules. Workplace-plan distributions depend on plan terms and federal rules, and moving money can affect protections or early-access options. Verify the consequences before treating a rollover as routine.

The annual limits apply separately: contributing to a 401(k) does not by itself consume the IRA contribution limit. A person who is eligible and has sufficient compensation and cash flow may contribute to both, subject to each account’s rules and the combined IRA limit.

A practical review can begin with the workplace match, then compare the plan’s costs and investments with an IRA, decide how much pre-tax and Roth exposure fits the tax plan, and preserve enough accessible savings for near-term needs. This is a framework for investigation, not a universal contribution order.