401(k) plans in plain English
A 401(k) is an employer-sponsored defined contribution retirement plan. Eligible employees can direct part of their compensation into an individual plan account and invest among the options the plan offers.
The account balance—not a promised monthly pension—determines the participant's benefit. Results depend on contributions, employer funding, investment returns, fees, withdrawals, and time.
The Summary Plan Description and plan documents control eligibility, match, vesting, investments, loans, and distributions.
Traditional and Roth contributions
Traditional 401(k) elective deferrals generally reduce current federal taxable income, while distributions are generally taxable later. They still commonly remain subject to Social Security and Medicare tax when contributed.
A plan may offer designated Roth contributions. These are made after tax; qualified distributions of contributions and earnings are generally tax-free.
Traditional and Roth deferrals share one employee annual limit. The tax choice does not change the investment itself, and a participant can split contributions if the plan allows.
2026 contribution limits
For 2026, the IRS employee elective-deferral limit for traditional and safe-harbor 401(k) plans is $24,500. Participants age 50 or older by year-end can generally make an additional $8,000 catch-up contribution if the plan permits.
For participants ages 60 through 63 in 2026, the higher statutory catch-up limit is $11,250. Special Roth treatment can apply to catch-up contributions for certain higher earners, so confirm current payroll and plan rules.
The general 2026 annual-additions limit covering employee deferrals, employer contributions, and forfeitures is $72,000, excluding permitted catch-up contributions and subject to compensation and plan rules.
Limits change, and special plans can differ. Verify the current IRS table each year.
Contributions across multiple jobs
The employee elective-deferral limit generally applies across the participant's 401(k), 403(b), and certain other elective deferrals, even when employers are unrelated. Payroll systems at separate employers do not automatically coordinate.
The annual-additions limit can apply separately to plans of unrelated employers, subject to controlled-business and other rules.
Track year-to-date deferrals after changing jobs and correct an excess promptly under IRS and plan procedures.
Employer match
An employer may match employee contributions using a formula, such as a percentage of pay up to a stated contribution level. Other employers make nonelective or profit-sharing contributions, and some make no contribution.
A participant who contributes below the amount needed for the full match can leave compensation on the table. But “always max the match” still requires enough cash flow for essentials and high-priority debt.
Match timing matters. Some employers match each pay period and provide a year-end true-up; others may not. Front-loading contributions can reduce match if there is no true-up.
Vesting
Employee contributions and their earnings are always fully vested. Employer contributions can vest immediately or over a schedule allowed by law.
Leaving a job before full vesting can forfeit the unvested employer portion. The account interface may display total balance and vested balance separately.
Review the plan's service-credit and vesting rules before a voluntary departure. Safe-harbor and certain other required employer contributions can have different vesting treatment.
Investment choices
401(k) menus commonly include target-date funds, stock and bond funds, stable-value or money-market options, and sometimes company stock or a brokerage window.
Choose an allocation based on time horizon, risk capacity, total household portfolio, costs, and the role of other retirement accounts. A target-date fund is a diversified one-fund option, but funds with the same date can have different glide paths, fees, and risk.
Automatic enrollment or a default investment is a starting setting, not a personalized recommendation.
Fees
Participants can pay investment expense ratios, recordkeeping, administration, advice, transaction, loan, or managed-account fees. Small percentage differences compound over decades.
The Department of Labor requires participant disclosures describing plan and investment fees. Compare net performance, services, diversification, and risk—not expense ratio alone.
Employer-paid fees can later shift to participants, and former employees may face different account charges.
Loans
Some plans allow participant loans within federal and plan limits. Repayments generally return principal and interest to the participant's account, but the loan removes money from market exposure and can create fees and opportunity cost.
Job separation can accelerate repayment or cause an unpaid amount to become a taxable distribution or plan-loan offset under applicable rules.
A loan is not free simply because interest returns to the account. Compare it with alternatives and preserve retirement assets where possible.
Hardship and early withdrawals
Plans may permit hardship distributions or other in-service withdrawals. A taxable distribution can trigger ordinary income tax and an additional tax before age 59½ unless an exception applies.
Exceptions are specific; being financially difficult does not automatically waive tax. A hardship distribution permanently removes assets and future compounding from the account.
Request the plan's written options and consult current IRS guidance before acting.
Changing jobs
Common options for a vested balance include leaving it in the former plan, rolling it directly to a new employer plan that accepts rollovers, rolling it to an IRA, or taking a distribution.
A direct rollover generally avoids mandatory withholding and the 60-day redeposit risk associated with an eligible distribution paid to the participant.
Compare fees, investment options, creditor protections, withdrawal rules, loan access, service, and consolidation. An IRA is not automatically better, and cashing out can create tax and lost growth.
Required minimum distributions
401(k) balances are subject to required minimum distribution rules. Current rules can allow some non-owner employees to delay distributions from a current employer's plan until retirement, while prior-plan and IRA rules differ.
Roth 401(k) accounts no longer require lifetime RMDs for the original owner under current federal rules, but beneficiaries remain subject to distribution rules.
Confirm deadlines with the plan and current IRS guidance; missing an RMD can trigger excise tax.
Beneficiaries and records
The beneficiary designation can control who receives the account and may override a will. Spousal-consent rules can apply.
Review designations after marriage, divorce, birth, death, or estate-plan changes. Keep plan contacts, statements, cost basis for any after-tax contributions, and rollover confirmations.
Inherited-account rules are complex and depend on beneficiary type and timing.
A practical contribution order
A common framework is:
- stabilize essential cash flow and capture the affordable full match;
- build emergency reserves and address high-cost debt;
- compare additional 401(k), IRA, and HSA opportunities;
- increase contributions automatically with pay raises; and
- rebalance and review fees periodically.
The right traditional-versus-Roth split depends on current and future tax rates, income, deductions, state tax, estate goals, and flexibility.
Common mistakes
Do not confuse the employee limit with the combined plan limit. Do not assume employer money is fully vested. Do not leave contributions in cash accidentally.
Avoid concentrating retirement wealth in employer stock, ignoring beneficiary forms, or cashing out during every job change.
A 401(k) is a legal and tax wrapper around contributions and investments. Its value comes from disciplined saving, appropriate diversification, controlled fees, and avoiding unnecessary leakage.