401(k) Employer Match: How It Works and How People Miss It
In short
Match formulas like "50% of 6%" can mean less than they sound. How to read yours, and the maxing-out mistake that forfeits part of it.
An employer match is extra pay that only shows up if you contribute to your 401(k). Contribute too little and you leave some of it with your employer. The good news is that one number, the percent that earns the full match, tells you the minimum worth contributing.
Reading Your Match Formula
A match formula has two parts: how much the employer adds per dollar you put in, and the most of your pay it applies to. Here are four common formulas, for someone earning $75,000:
| Formula | You contribute | Employer adds | On $75,000 |
|---|---|---|---|
| 100% of the first 3%, then 50% of the next 2% | 5% | 4% of pay | $3,000 |
| 100% of the first 4% | 4% | 4% of pay | $3,000 |
| 50% of the first 6% | 6% | 3% of pay | $2,250 |
| 100% of the first 6% | 6% | 6% of pay | $4,500 |
The first row is the "safe harbor" match many plans use, because it lets the plan skip some annual IRS testing. Notice that "50% of 6%" sounds generous but adds less than "100% of 4%", and you have to contribute more to get it.
How Much You Leave Behind
Take the safe harbor formula and a $75,000 salary. Contributing 3% gets a 3% match, $2,250. Contributing 5% gets the full 4%, $3,000. So the person contributing 3% leaves $750 a year on the table. Over 30 years at a 6% return, $750 a year grows to about $59,000.
And the extra 2% costs less than it looks. At a 22% federal rate and 5% state rate, the extra $1,500 contribution lowers take-home pay by about $1,095, and brings in $750 of match.
The Front-Loading Trap
Worked Example
$150,000 salary, paid every two weeks, safe harbor match, no true-up
Same $24,500 from the employee, but front-loading loses $2,076.92 of match. The employer adds $230.77 each paycheck at 4% of $5,769.23, and paychecks 18 through 26 get nothing because contributions have stopped.
Some plans fix this with a true-up: after the year ends, they compare the match you got with the match your full-year pay and contributions earned, and deposit the difference. If your plan has one, front-loading is fine. If it doesn’t, spread your contributions so the last one lands on the last paycheck. Your summary plan description says which you have.
Vesting: When the Match Is Really Yours
Your own contributions are always 100% yours. Matching money can come with a vesting schedule. For a match, the law allows up to a 3-year "cliff" (nothing until year 3, then all of it) or a 6-year graded schedule (20% a year from year 2). Traditional safe harbor matches must vest immediately. If you are thinking of leaving a job, check how much of the match you would keep.
What This Doesn't Cover
This guide assumes the match is figured each paycheck on your contributions as a percent of pay. Some plans match once a year, match on a different definition of pay (for example, excluding bonuses), make a non-elective contribution that doesn’t depend on what you put in, or offer a Roth match. The dollar figures ignore investment fees. Your plan documents or HR team can confirm how your match works.
Check Your Own Match
Pick your match formula and see whether you get all of it, what it costs per paycheck, and whether you hit the limit too early.
Open the 401(k) Paycheck CalculatorSources: IRS 401(k) plan overview (safe harbor plans and vesting); IRS release IR-2025-111 (2026 limit).
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