Dollar Almanac

401(k) True-Up Calculator

Updated

Contributing more, earlier, can leave money on the table. This works out how much, and whether your plan gives it back.

If your plan matches each pay period and you reach the $24,500 deferral limit before December, the paychecks after that are matched with nothing, and unless your plan has a true-up provision that match is never paid.

Base pay. Bonuses change when the limit is reached, and are not modelled.

How often you are paid

The share of each paycheck going into the plan.

A dollar-for-dollar match is 100%. A fifty-cent match is 50%.

The formula stops matching above this share. Together these read as “100% of the first 5%”.

Does your plan have a true-up?

A provision that reviews the whole year and pays any match you missed. If you do not know, leave this as it is.

From 50 the deferral limit is higher, which changes the rate that paces it evenly.

Employer match you give up

$5,000.04

Match you would earn spread evenly
$10,000.08
Match you actually earn
−$5,000.04
Given up
$5,000.04
§402(g) on your own deferrals (this is what stopped you)
$24,500 of $24,500
§415(c) on everything landing in the account
$29,500 of $72,000
§401(a)(17) on the pay the plan may consider
$200,000 of $360,000

Your deferral reaches the limit in pay period 12 of 24. Spreading the same total across the year at 12.25% earns every period's match.

critical: You are giving up employer match

Your deferral reaches the annual limit before the year ends. Every pay period after that contributes nothing, so there is nothing in it to match. The same total spread evenly earns all of it. Your employer offered this money and the plan will not pay it.

What this does not cover (3)

info: The match is assumed to be calculated each pay period

That is how most plans work, and it is what makes front-loading costly. A plan that computes match annually has no forfeiture to begin with. Your plan document says which.

info: Pay is assumed even across the year

Bonuses, commission and mid-year raises all move the date the limit is reached. A single bonus deferral can bring it forward by months.

info: An estimate, not advice

Your plan document governs the match formula, the true-up and the per-period rules. Confirm with your administrator before changing an election.

What this assumes

Assumption set limits 2026

Pay periods a year
24
Age reached this year
40
Match calculated
Each pay period
Limits
Notice 2025-67
Limit year
2026

Limits from Notice 2025-67, read August 19, 2026

How this works

Most plans work out the employer match one pay period at a time, on what you contributed in that period. That detail is the whole problem. Reach the annual limit in August and the September paycheck has nothing in it to match, so nothing is matched. You have not contributed less over the year. You have contributed it all in the part of the year the match was watching, and then stopped while it kept watching.

A true-up is the provision that fixes this. It reviews the whole year once it has ended and pays whatever match the per-period calculation missed. Many plans have one. Many do not, and the difference between them is not something you find out by contributing.

Three ceilings, not one

Contribution rules are usually described as though there were a single annual limit. There are three, they come from different subsections, and they stop different people:

  • §402(g), what you may defer. The one everybody knows. It caps your own contributions from pay, and it is higher from the year you turn 50.
  • §415(c), everything landing in the account. Your deferrals and every employer dollar together. It binds people whose employer contributes generously, and most people have never heard of it.
  • §401(a)(17), the pay the plan may consider. This one does not limit your contribution at all. It limits the compensation your match is calculated on, so above it a percentage match stops growing with your salary.

The results show all three, each with its own figure, and mark the one you have reached. That matters most at the top end. Someone stopped by the compensation limit is usually told they “hit the contribution limit”, which is a different rule with a different cause, and it points them at a fix that does not exist.

Worked example

Priya earns $200,000 and is paid twice a month, so $8,333.33 a period. She defers 25% to “max out early”, and her employer matches 100% of the first 5% of pay.

At 25% she puts in $2,083.33 a period and reaches the $24,500 limit in period 12, halfway through the year. The match is 5% of pay, or $416.67 a period, but only in the periods where she actually contributes:

12 periods matched × $416.67 = $5,000.04, against $10,000.08 for a full year.

She gives up $5,000.04 of employer match. The same $24,500, spread evenly at 12.25%, would have earned all of it. Unless her plan has a true-up, that money is simply not paid.

The limit that is not the contribution limit

Marcus earns $500,000 in the same plan. He reaches the deferral limit in period 5, so he gives up $12,437.43. But the figure that surprises him is a different one: the plan may only consider compensation up to $360,000, so his 5% match is 5% of that and not of his salary.

$360,000 × 5% = $18,000 is his ceiling on match, not $500,000 × 5% = $25,000.

Two separate rules stopped Marcus, and telling him only that he “hit the contribution limit” would be true and useless. The deferral limit is one he can pace around. The compensation limit is not, and it is the one costing him more.

What this does not tell you

Whether front-loading is right for you anyway. Money in the market earlier compounds for longer, and someone expecting to leave mid-year may prefer to secure the contribution while they can. This prices the cost so the trade is against a number rather than a feeling.

It assumes even pay across the year and a match calculated each pay period. Bonuses and commission reach the limit far earlier than a salary alone; a plan that matches annually has no forfeiture to begin with. Your plan document governs both, and it also governs whether a true-up exists.

Sources

References used to explain this page. Listing a publisher is not a claim that they endorse it.

Figures are transcribed from these documents directly. Where a value has not been verified against its source, this page shows no number rather than an estimate.

Questions

What is a 401(k) true-up?
A provision that reviews your whole year after it ends and pays any employer match you missed by contributing unevenly. Most plans calculate match on each pay period in isolation, so a period where you contributed nothing is matched with nothing. A true-up looks at the year as a whole instead and makes up the difference. Plans that have one usually pay it in the first quarter of the following year.
Why would I miss match by contributing more?
Because the match is calculated per pay period, not per year. If your deferral rate is high enough to reach the annual limit in August, you contribute nothing from September, and there is nothing in those paychecks for your employer to match. You have not contributed less overall, but you have compressed it into a part of the year, and the match only exists in the periods where a contribution does.
How do I find out whether my plan has one?
The summary plan description is where it is written, usually under the section on employer contributions. If it is not obvious, the question to put to your plan administrator is narrow: does the plan true up matching contributions after the end of the year. It is worth asking rather than assuming, because the two answers differ by whatever figure this calculator shows you.
Is front-loading ever the right move?
It can be. Money in the market earlier has longer to compound, and someone who expects to leave mid-year may prefer to secure the contribution while they can. What matters is that it is a trade rather than a free choice: this page prices the side of it that is usually invisible so the comparison is against a number.
What are the three limits, and which one applies to me?
They are separate rules that bind different people. Section 402(g) caps what you may defer from your own pay. Section 415(c) caps everything that lands in the account in a year, your contributions and every employer dollar together. Section 401(a)(17) caps the compensation the plan may consider, which does not limit your deferral at all but does limit the pay your match is calculated on. The results show all three, and mark the one you have actually reached.
I earn well above the compensation limit. What does that change?
Your match is worked out on the capped figure, not on your salary. A 5% match on a $500,000 salary is 5% of $360,000. What surprises people is that this is not a contribution limit at all, so there is no deferral rate that gets around it, and a calculator reporting only the deferral limit hands high earners the wrong explanation for what stopped them.
Does this include catch-up contributions?
Yes. From the calendar year you turn 50 the deferral limit is higher, and higher again in the years you turn 60 through 63. A higher ceiling means a higher rate is needed to pace it evenly across the year, which is the opposite of what most people assume when they hear the limit went up.
Where does what I type go?
Nowhere. The whole calculation runs in your browser. The figures are encoded into the address bar so a scenario can be shared or bookmarked, and nothing is sent anywhere or stored on a server.

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