How Does a 401(k) Match Work?

By Derek Holt · Last checked October 12, 2026

The short version

A match only exists if you put money in first. The IRS describes it this way: if the plan document permits, your employer can make matching contributions for an employee who contributes elective deferrals, meaning money taken out of your own paycheck and put into the plan.

So the order of events is simple. You choose a percentage of your pay. That comes out of each paycheck. Your employer then adds money on top, based on a formula in the plan.

There is no single national formula. Each plan writes its own, and it lives in the plan document and the Summary Plan Description, often shortened to SPD.

How a match formula reads

The IRS gives a plain example of a formula: a plan “might provide that the employer will contribute 50 cents for each dollar” employees choose to defer.

A more detailed formula appears in the IRS rules for one type of plan, called a qualified automatic contribution arrangement. If an employer uses that design and picks a match, it must contribute at least:

• 100 percent of what you put in, on the first 1 percent of your pay, plus
• 50 percent of what you put in, on the next 5 percent of your pay (from 1 to 6 percent).

That formula is required only for that one plan type. Your employer may use a different formula, a cap, or no match at all. It is useful here because it shows how a match formula is built: a rate, and a limit on how much of your pay it applies to.

Worked numbers

This is an illustration, not a real person or a real plan. Aniyah earns $40,000 a year. Her plan uses the formula above. Here is what different choices produce in a year.

Two things stand out. At 0 percent she gets nothing from the employer. Past 6 percent, the match stops growing, because the formula only applies to the first 6 percent of her pay. Anything above that is still her savings, just without extra employer money attached.

Vesting: when the match is actually yours

Vesting means ownership. The IRS puts it bluntly: money you are 100 percent vested in is yours, and “the employer cannot forfeit, or take it back, for any reason.”

Your own contributions are always 100 percent vested. The match is different. The IRS says matching contributions in a traditional 401(k) can be subject to a vesting schedule, or be vested immediately. The plan document decides.

The IRS shows two example schedules side by side:

A “year of service” is defined by the plan. The IRS says it is generally 1,000 hours worked over 12 months, and that employers can count service in different ways.

Some plans skip the wait. The IRS says a safe harbor 401(k) must provide employer contributions that are fully vested when made. In the qualified automatic contribution design above, you must be 100 percent vested in the required employer money after no more than 2 years of service.

Back to the illustration. Say Aniyah’s plan used the graded schedule instead, and she left after 2 full years of service. She keeps every dollar she contributed, plus 20 percent of the match. The other 80 percent of the match may be forfeited. Under the cliff schedule she would keep none of the match until year 3.

The 2026 limits

The IRS sets two limits for 2026:

• Your own contributions: $24,500 in 2026 for traditional and safe harbor 401(k) plans. Your plan may set a lower limit.
• Everything added to your account: the lesser of 100 percent of your pay or $72,000 in 2026. This total includes your contributions and the match, but not catch-up contributions.

The figures change with cost-of-living adjustments, so check the IRS page for the current year.

Taxes and paycheck details

With a regular pre-tax 401(k), the IRS says your contributions are generally not subject to federal income tax withholding when they come out of your pay. They are still subject to Social Security and Medicare taxes. The amount shows up on your Form W-2, which our guide to reading your first W-2 walks through.

Plans may also offer a Roth option. The IRS says Roth contributions are taxed under rules similar to a Roth IRA, which works differently from the pre-tax version. Ask HR which options your plan has.

If you were signed up automatically

A plan can enroll you without asking. The IRS says an employer must give you the option, before anything is withheld, to contribute nothing or a different amount. Some plans let you take back automatic contributions within 90 days of the first one.

If you were enrolled automatically, check two things: the percentage being taken out, and whether that percentage is enough to get the full match under your plan’s formula.

Before you take money out

The IRS says amounts withdrawn from a retirement plan before age 59 and a half generally owe an additional 10 percent tax, on top of regular income tax, unless an exception applies. Moving the money into another plan or an IRA within 60 days is one of the listed exceptions. If you change jobs, ask the old plan about a rollover before you cash out.

Questions to ask HR

• What is the match formula, in writing?
• When am I eligible to join, and when does the match start?
• What is the vesting schedule, and how does the plan count a year of service?
• Was I enrolled automatically, and at what percentage?
• Is there a Roth option?
• Where can I see my vested balance?

Related reading

Before you pick a percentage, see how it fits in a budget for your first paycheck. If you are still deciding on the job, read the offer for the date your 401(k) eligibility actually begins.