401k Match True-Up: How Much Match You Lose by Front-Loading (Formula + 2027 Limits)
Max out your 401(k) by August and you could hand back $1,904 of free money before the year is over. That’s the math for someone earning $150,000 with the most common employer match formula who sets a 30% deferral rate in January. This post shows you how a 401k match true-up works, the one-line formula for figuring out how much match you lose by front-loading, and how to set your contribution rate for 2027 so you collect every dollar your employer has promised.
The timing matters this week. On November 12, 2026, the IRS announced in Notice 2026-66 that the 401(k) employee deferral limit rises to $25,500 for 2027, up from $24,500 in 2026. The catch-up for workers 50 and older rises to $8,500, and the higher catch-up for ages 60 to 63 is $11,750. Most people will update their payroll elections over the next few weeks, which makes now the cheapest moment to get the match math right.
The Problem: Your Match Is Usually Calculated Per Paycheck
Most employer matches are promised as an annual number (say, “50% of the first 6% of pay”) but paid out paycheck by paycheck. Every time payroll runs, the plan looks at what you deferred from that check and matches it. When you hit the annual IRS limit, your deferrals stop, and in a plan without a true-up, so does the match. Your remaining paychecks carry no contribution, so they carry no match.
The match is a big deal for most savers. According to Vanguard’s How America Saves 2025 report (covering 2024 plan data), 86% of the plans it administers offer a matching contribution. The average promised match is worth 4.6% of pay (median 4.0%), and the most common single formula is exactly the one in the opening example: $0.50 per dollar on the first 6% of pay. Workers need to defer an average of 6.5% to get the maximum match.
A true-up fixes the per-paycheck problem. As PLANSPONSOR explains, a true-up is an optional employer contribution, usually made at year-end or in the first couple of months of the following year, that makes up the difference between the match you actually received and the full match you were eligible for based on your annual pay. The catch is the word “optional.” In a 2017 PLANSPONSOR National Conference poll, only 44% of plan sponsors said they offered one. A Deloitte benchmarking survey cited in the same piece put the figure at 54%. Either way, roughly half of employers don’t true up, and many employees have no idea which group they’re in.
Who gets hurt? Mostly high savers. Vanguard reports that 14% of participants contributed the maximum allowed in 2024. Those are exactly the people who might set an aggressive deferral rate, hit the cap in the summer, and quietly lose part of the match. (If you’re one of them, the same people also tend to run into the new Roth catch-up rule for high earners, so it’s worth checking both at once.)
The Quick Answer: A One-Line 401k Match True-Up Formula
If your plan does not offer a true-up and matches per pay period, the lost match is:
Match per paycheck = Match rate × Match cap % × Gross pay per check
And the deferral rate that lets you max out and keep the full match is just the limit divided by your salary:
Example: $25,500 ÷ $150,000 = 17%
Round up to the nearest whole percent your payroll system allows (or pick the percentage just below and top off the final paycheck). Anything that spreads contributions across all your paychecks preserves the match. Anything that finishes early leaves money on the table unless your plan trues up.
Here’s how I think about this personally. I’m a software engineer, and I manage my own 401(k) and IRAs without an advisor. A few years back I set my deferral rate high in January, mostly because front-loading felt like the disciplined, “time in the market” thing to do. I only caught the problem because I build little spreadsheets for everything and noticed my employer contributions had stopped in the fall. My plan happened to true up the following February, so I got lucky. But it was luck, not planning, and it sent me down a rabbit hole on how many people never notice.
Scenarios: What Front-Loading Costs at Different Deferral Rates
Let’s run the numbers. Assumptions: $150,000 salary, 26 biweekly paychecks ($5,769.23 gross each), 2027 limit of $25,500, employer match of 50% on the first 6% of pay (Vanguard’s most common formula), no true-up, and match calculated each pay period. The maximum annual match is 3% of salary, or $4,500. Match per full paycheck is $173.08.
| Deferral rate | Per paycheck | Limit hit on paycheck # | Match received | Match lost (no true-up) |
|---|---|---|---|---|
| 17% (even spread) | $980.77 | 26 (last check) | $4,500 | $0 |
| 20% | $1,153.85 | 23 | $3,865 | $635 |
| 25% | $1,442.31 | 18 | $3,115 | $1,385 |
| 30% | $1,730.77 | 15 | $2,596 | $1,904 |
| 50% | $2,884.62 | 9 | $1,558 | $2,942 |
Illustrative calculation by MoneyAndPlanet using the IRS 2027 limit and Vanguard’s most common match formula. Your plan’s formula and pay schedule will change the dollar amounts.
Notice the shape of the curve. Going from 17% to 20% looks harmless, but it still costs $635. At 30%, you lose more than 40% of the match. At 50%, a setting some aggressive savers use to “get it over with,” you keep barely a third of it.
Scenario 1: The bonus spike
Front-loading isn’t always deliberate. Suppose your deferral rate is applied to a large annual bonus paid in March. A 15% election on a $40,000 bonus sends $6,000 into the plan on a single check, pulling your limit date several pay periods earlier than you planned. Whether the match also applies to that bonus depends on your plan’s definition of “eligible compensation,” which is spelled out in the summary plan description. Some plans match on base pay only, some include bonuses. If yours includes them and you set a separate (lower) bonus deferral rate, you can often keep your limit date in December.
Scenario 2: The mid-year job switch
The deferral limit is per person, not per employer. If you contribute $15,000 at Job A by June and then start Job B, you only have $10,500 of room left for 2027. Job B’s payroll system doesn’t know about Job A, so if you elect the same rate you were using before, you can blow through the limit by October and lose Job B’s match for the rest of the year (or worse, over-contribute and have to request a corrective distribution). Recalculate the even-spread rate using your remaining room divided by your remaining salary at the new employer. Job switchers should also check the new plan’s 401(k) vesting schedule, because unvested match you leave behind is another form of lost money.
Scenario 3: You’re 50 or older
Catch-up contributions change the picture. For 2027, a worker aged 50 to 59 can defer up to $25,500 + $8,500 = $34,000. Many plans “spill over” contributions above the regular limit into the catch-up bucket automatically, so your deferrals continue past the $25,500 mark. Whether the employer matches those catch-up dollars is a plan-document question, so check before you assume. If the plan does match them, your even-spread rate is $34,000 divided by your salary, not $25,500.
Curious what an extra $1,900 a year of employer match grows into by retirement?
Why a Missing 401k Match True-Up Compounds Into Real Money
$1,904 sounds like a rounding error next to a six-figure salary. But it’s a recurring loss, and it’s lost inside a tax-advantaged account where it would have grown untouched. Purely as an illustration (not a forecast): $1,904 a year invested for 20 years at a hypothetical 7% annual return grows to roughly $78,000. That’s the cost of one payroll setting that nobody revisited.
There’s also a behavioral angle here, which is the part I find most interesting. Front-loading feels virtuous: it’s saving more, sooner. Our brains reward that feeling and stop asking questions. It’s the mirror image of the inertia we covered in our piece on present bias and retirement contributions: one group under-saves because the future feels abstract, and another group over-optimizes the visible metric (“maxed out by June!”) while missing the less visible one (total employer dollars). Both are fixed by the same tool, a one-time calculation followed by a set-and-forget payroll election.
And yes, there’s a legitimate counterargument. Front-loading gets money invested earlier, and markets have historically risen more often than not, so earlier money has more expected time to grow. But the math rarely favors it when match is at stake. Getting $25,500 invested a few months sooner earns you a few months of expected return on that sum, while a lost 3% match is a guaranteed, immediate 50% return on the matched dollars that you simply never receive. Unless your plan trues up, the match wins.
How to Check Your Plan and Set Your 2027 Rate
You can do this in 15 minutes during open enrollment or when you update your elections for the new limit:
- Find the match formula and the 401k match true-up language. Look in your plan’s summary plan description (SPD), usually in the benefits portal. Search the document for “true-up,” “annual match,” or “match calculation period.” If the match is computed on an annual basis, front-loading is safe. If it says “each payroll period” with no true-up, it isn’t.
- Confirm what counts as eligible pay. Base salary only, or bonuses and commissions too? This determines both your match ceiling and how a bonus check shifts your limit date.
- Calculate your even-spread rate. Divide the 2027 limit ($25,500, or more with catch-up) by your expected eligible pay. Round to what payroll allows.
- Set a separate bonus deferral rate if your plan allows it. This keeps a single large check from pulling your limit date forward.
- Revisit after any raise or job change. A raise mid-year with an unchanged percentage pushes you toward the limit faster. A job change resets your payroll but not your annual limit.
- Verify in December or January. Compare your year-to-date employer contributions to the formula. If you’re short and your plan has a true-up, confirm it gets deposited; if it doesn’t, adjust next year’s rate.
Once the match is secured, the next decision is where those deferrals go. Our breakdown of traditional vs. Roth 401(k) tax bracket math walks through which bucket makes sense at different incomes. Note that employer match has historically gone in pre-tax regardless of your election, though SECURE 2.0 now allows plans to offer Roth matching contributions if they choose to.
| What your SPD says | Is front-loading safe? | What to do |
|---|---|---|
| Match calculated annually | Yes | Contribute on whatever schedule you like |
| Per-paycheck match with year-end true-up | Usually (check eligibility rules, e.g., employed on Dec 31) | Front-load if you want; confirm the true-up arrives |
| Per-paycheck match, no true-up | No | Use the even-spread rate |
| Document is unclear | Assume no | Ask HR or the recordkeeper in writing |
One caveat worth flagging: some 401k match true-up provisions only pay if you’re still employed on the last day of the plan year. If you’re planning to leave in, say, November, a front-loaded schedule could forfeit the true-up entirely. In that case, the even-spread rate is the safer default.
FAQ
How do I know if my 401(k) has a true-up?
Check your summary plan description for the words “true-up” or for language saying the match is calculated on an annual (plan-year) basis. If it’s unclear, ask HR or your plan’s recordkeeper. You can also check your account history: if employer contributions stopped the same pay period your deferrals stopped and then a lump sum showed up early the next year, your plan trued you up.
Is it ever better to front-load 401(k) contributions?
Front-loading makes sense when your plan calculates the match annually or offers a true-up you’re confident you’ll qualify for, or when your employer offers no match at all. In those cases, investing earlier simply gives your money more time in the market. Without a true-up, the guaranteed match you’d lose usually outweighs the expected benefit of investing a few months sooner.
What is the 401(k) contribution limit for 2027?
The IRS set the 2027 employee deferral limit at $25,500, up from $24,500 in 2026. Workers 50 and older can add an $8,500 catch-up, and workers aged 60 to 63 can use a higher $11,750 catch-up instead. The IRA contribution limit stays at $7,500.
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