401(k) Basics for 2026
A 401(k) is three separate advantages stapled together: a tax break, an employer subsidy, and decades of compounding in a container you are discouraged from raiding. Understanding which of the three is doing the work at each stage makes most 401(k) decisions straightforward. The numbers below are the 2026 limits; the 401(k) growth calculator projects your own plan.
The 2026 limits
You can defer up to $24,500 of salary into a 401(k) in 2026 (up from $23,500 in 2025). Savers age 50 and older can add a $8,000 catch-up, and those turning 60 through 63 during the year get a larger $11,250 catch-up in place of the standard one where the plan allows it. Employer money does not count against your personal limit — the match rides on top, bounded only by the $72,000 cap on combined employee and employer additions. Very few people hit these ceilings; for most, the binding constraint is their budget, not the IRS.
The match is the highest-return investment you will ever see
A typical arrangement — say, 50 cents or a dollar per dollar on the first few percent of salary you contribute — is an instant 50% or 100% return, before the market does anything. No other legal investment resembles that. This makes the first rule of 401(k) strategy nearly universal: contribute at least enough to collect the full match, even when money is tight, because declining it is refusing part of your compensation. Two caveats deserve a look in your plan documents: vesting schedules (employer money may only become fully yours after some years of service) and match timing (some employers match per paycheck, which can shortchange people who max out early in the year unless the plan has a true-up).
Traditional vs. Roth in one honest paragraph
Traditional contributions skip tax now and are taxed on withdrawal; Roth contributions are taxed now and withdraw tax-free. Ignore every heuristic except this one: compare your marginal tax rate today against the rate you expect when you withdraw. Higher now, or peak-earnings years? Traditional wins. Early career, low bracket, expecting to earn more later? Roth wins. Genuinely unsure? Splitting is a legitimate answer, not a cop-out — it diversifies against future tax rates the same way you diversify investments. Your marginal rate is the number that decides this; our marginal vs. effective guide shows how to find it.
What compounding actually does
Take someone earning $80,000 who contributes 10% with a 4% match, earning 7% a year for 30 years. They put in $240,000 of their own money; the employer adds $96,000. The ending balance is about $1,057,961 — of which $721,961 is growth, more than double everything both parties contributed. Run the same saver but start ten years later and the balance is roughly $459,150: the missing decade costs more than half the final amount, despite only a third fewer contributions. That asymmetry — early dollars matter disproportionately — is the entire case for starting before you feel ready.
Common mistakes worth avoiding
Cashing out when changing jobs is the expensive one: withdrawals before 59½ generally owe income tax plus a 10% penalty, and the real cost is the compounding the money never does — roll it into the new plan or an IRA instead. Forgetting to actually invest contributions (they can sit in a money-market default) quietly wastes years. And obsessing over fund choice before fixing the contribution rate gets the order backwards: the percentage you save dominates every other decision by a wide margin in the early decades.
Limits are from the IRS 2026 cost-of-living adjustments; source URLs are kept with the data in the site repository. The examples use the same simplified model as our calculator — steady salary, annual compounding, no fees. General information, not investment advice.