Written by the TaxPlain Editorial Team · Reviewed for accuracy · Last updated August 2026
⚠️ Educational only. TaxPlain does not provide tax, legal, or financial advice. Always consult a qualified tax professional about your specific situation.
What this is
A 401(k) is an employer-sponsored retirement savings plan that lets you set aside part of your paycheck before it hits your bank account. Contributions are typically made pre-tax, which lowers your taxable income for the year you contribute, and the money grows tax-deferred until you withdraw it in retirement.
Many employers offer a matching contribution — meaning they add money to your account based on how much you contribute, up to a certain percentage of your salary. This is essentially free money, and missing out on a full match is one of the most common retirement-planning mistakes.
Some plans also offer a Roth 401(k) option, which flips the tax treatment: you contribute after-tax dollars now, but qualified withdrawals in retirement are completely tax-free. You can learn more about how that compares in our Roth IRA guide.
Who it affects
✓ Applies to
Anyone whose employer offers a 401(k) plan and who chooses to contribute a portion of their paycheck toward retirement savings.
↑ Also applies to
Anyone considering an early withdrawal, a job change, or a rollover — all of which trigger different tax rules.
📅 2026 CONTRIBUTION DEADLINE
Unlike an IRA, you can't make 401(k) contributions after the calendar year ends. Your last chance to contribute for 2026 is your final paycheck of the year, so review your contribution rate well before December if you're trying to hit the max.
Contribution limits
How much can you contribute in 2026?
For 2026, the employee contribution limit is $24,500. This is the maximum you can personally elect to defer from your paycheck into your 401(k) across the whole year, whether it goes to a traditional or Roth 401(k) or split between both.
Standard employee limit — $24,500 for anyone under 50.
Catch-up contribution (age 50+) — an additional $8,000, bringing the total to $32,500.
Super catch-up (ages 60–63) — a higher catch-up amount applies under SECURE 2.0 for this age band specifically; check your plan administrator for the exact 2026 figure, since it's indexed separately from the standard catch-up.
Employer match doesn't count toward your personal limit — your $24,500 cap covers only what comes out of your own paycheck.
Combined employee + employer limit — there's a separate, much higher cap on total contributions from both you and your employer combined, which matters mostly for high earners with generous matches or profit-sharing plans.
Roth vs traditional split — you can divide your $24,500 however you like between Roth and traditional contributions, but the combined total still can't exceed the limit.
Related forms often involved
A few other forms and accounts tend to come up alongside your 401(k), especially around tax season or when changing jobs.
Form 1099-R — issued if you take a distribution or rollover from your 401(k) during the year.
W-2, Box 12 — your annual 401(k) contributions are reported here with code D (traditional) or AA (Roth). Related: our W-2 guide.
IRA — often used alongside or as a rollover destination for an old 401(k); see our IRA guide.
Withdrawal rules & common mistakes
⚠️ Cashing out early without knowing the penalty
Withdrawals before age 59½ are usually hit with a 10% early withdrawal penalty on top of regular income tax, which can eat a significant chunk of the balance.
⚠️ Misunderstanding the rule of 55
The rule of 55 only applies to the 401(k) from the employer you just left, if you leave in or after the year you turn 55. It doesn't apply to old 401(k)s from prior jobs or to IRAs.
What to do right now
Check your current contribution rate against the 2026 limit, especially if you're 50 or older and eligible for catch-up contributions. If you're considering a withdrawal or rollover, confirm which rule applies to your situation before you initiate anything — the difference between an eligible rollover and a cash-out can mean thousands in penalties and taxes. If you're job-hunting or recently changed employers, review your W-2 to confirm contributions were reported correctly.
Questions to ask your tax professional
01Am I on track to hit the 2026 contribution limit, and does it make sense for my situation?
02Should I split my contributions between traditional and Roth, and in what proportion?
03If I leave my job this year, does the rule of 55 apply to me?
04What are my rollover options if I have an old 401(k) from a previous employer?
05Am I eligible for the age 60–63 super catch-up contribution, and how much is it this year?
Frequently asked questions
What is the 401(k) contribution limit for 2026?
For 2026, the employee contribution limit is $24,500. If you're 50 or older, you can add a $8,000 catch-up contribution. If you're between 60 and 63, a higher "super catch-up" limit may apply under SECURE 2.0.
Does my employer's match count toward my 401(k) contribution limit?
No. The $24,500 limit applies only to what you personally contribute from your paycheck. Employer matching contributions don't count toward your individual limit, but there's a separate, higher combined limit for total contributions from both you and your employer.
What is the rule of 55 for 401(k) withdrawals?
The rule of 55 lets you withdraw from your current employer's 401(k) penalty-free if you leave that job in or after the year you turn 55. It only applies to the 401(k) from the employer you just left, not old accounts or IRAs.
What's the penalty for withdrawing from a 401(k) early?
Withdrawals before age 59½ are generally hit with a 10% early withdrawal penalty on top of regular income tax, unless an exception applies, such as hardship, disability, or the rule of 55.
What's the difference between a 401(k) and a Roth 401(k)?
A traditional 401(k) is funded with pre-tax dollars and taxed on withdrawal. A Roth 401(k) is funded with after-tax dollars, so qualified withdrawals in retirement are tax-free. Many employers offer both within the same plan.