Employer match and vesting: leaving one month early is the financial equivalent of stepping on a Lego

By Tom, CPA · Updated October 25, 2026

TL;DR: Your own 401(k) deferrals are always 100% vested, but employer matching contributions can follow a vesting schedule: at most a 3-year cliff or a 6-year graded schedule (20% after 2 years, rising to 100% after 6). Safe harbor matches are fully vested immediately, or after 2 years in a QACA. Before quitting, check your vested percentage and whether the plan does a year-end true-up.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

The employer match is the closest thing to free money in personal finance, and vesting is the fine print that says "free, eventually." Leave a month before your next vesting milestone and the unvested match goes back into the plan, like stepping on a Lego while walking out the door: small, sharp, and completely avoidable.

Early retirees and job-hoppers are the most exposed, because they leave on purpose and often on a schedule. Here's how match formulas, true-ups and vesting schedules work, and how to time an exit without leaving money behind.

CPA Warning Label: Vesting is based on years of service as your plan defines them, not calendar dates on your badge. Read the plan's definition before timing a resignation around it.

Match formulas

Common formulas:

Matches are usually calculated per pay period. Not deferring enough to get the full match is like declining part of your salary. In 2026, employer matches can be made as Roth if the plan allows (a SECURE 2.0 option), in which case they're taxable to you when contributed.

True-up provisions

If the match is calculated per paycheck and you front-load deferrals, you can hit the $24,500 deferral limit in, say, August, and then get no match for the rest of the year. A true-up is a year-end calculation that tops up your match to what you'd have received on an annual basis.

• With a true-up, front-loading is fine.
• Without one, spread your deferrals to cover every pay period.
• Many true-ups require you to be employed on the last day of the plan year, which matters if you're retiring mid-year.
• Some plans also require 1,000 hours or last-day employment for the match itself, especially for profit-sharing contributions.

The plan's summary plan description (SPD) explains whether there's a true-up and any allocation conditions.

Cliff vs graded vesting

Your deferrals and their earnings are always 100% vested. Employer matching contributions in a non-safe-harbor plan must vest at least as fast as one of these schedules (IRC 411(a)(2)(B)):

Plans can be more generous, including immediate vesting. Safe harbor matches (non-QACA) must be 100% vested at all times; QACA safe harbor contributions must be fully vested after no more than 2 years of service. You also become fully vested at the plan's normal retirement age and if the plan is terminated.

A "year of service" for vesting is usually a 12-month period with at least 1,000 hours, but plans can use elapsed time instead. Check the SPD.

Timing your exit

• Find your vesting date. Your statement or plan website usually shows a vested percentage and the date of the next step.
• Count hours, not just dates, if the plan uses the 1,000-hour method: a computation period might end on the plan's year-end, not your hire anniversary.
• Weigh last-day rules for true-ups and profit-sharing.
• Consider bonuses, RSUs and severance on the same timeline. Vesting is rarely the only date that matters.
• Retiring at 55 or later? Leaving in or after the year you turn 55 can unlock the Rule of 55, which can make the exact year matter more than the month.

Illustration: one month too early

Illustration (assumptions): Fran earns $120,000 and her plan matches 100% of the first 4% with a 3-year cliff. Her third year of service ends on September 30. She plans to retire and is thinking about leaving on August 31.

• Match per year: $4,800. After almost three years plus growth, her match account is about $15,000.
• Leaving August 31: 0% vested, $0 of the match.
• Leaving October 1: 100% vested, $15,000.

One month of work is worth $15,000 plus her salary for the month. Even if she hates the job, that's a strong hourly rate. With a 6-year graded schedule, the difference between 3 and 4 years would be 20% of the match, smaller but still real.

What happens to unvested money

When you leave before full vesting, the unvested part is forfeited after a distribution or a break in service. Forfeitures stay in the plan and are typically used to pay plan expenses or reduce future employer contributions. If you're rehired within certain periods, some plans restore prior service (and sometimes forfeitures). Ask before assuming forfeited money is gone forever.

Questions to ask HR or the plan website

1. What's the exact match formula, and is it calculated per pay period or annually?
2. Is there a year-end true-up, and does it require last-day employment?
3. What vesting schedule applies to matching and to profit-sharing contributions?
4. How is a year of service counted: 1,000 hours in a computation period, or elapsed time?
5. What's my vested percentage today, and when is the next increase?
6. Does the plan count prior service if I was rehired or came from an acquired company?
7. Can employer contributions be made as Roth, and does the plan allow in-plan Roth conversions?

Write down the answers with the date. Plan rules change, and having a record of what you were told makes it easier to resolve a disagreement later.

A second illustration: graded vesting and a raise

Illustration (assumptions): Larry earns $90,000 and gets a 50% match on the first 6% of pay ($2,700 a year), on a 6-year graded schedule. After 4 years of service his match account is worth about $12,000, so he's 60% vested: $7,200.

• Stay one more year: 80% vested on about $15,000 = $12,000.
• Stay two more years: 100% vested on about $18,000 = $18,000.

Each additional year adds roughly $4,800 to $6,000 of vested money, on top of salary. If he's choosing between leaving now for a job with a bigger salary and immediate vesting, or staying for the schedule, the comparison is the vested money forgone versus the higher pay and the new employer's match. Graded schedules make the cost of leaving smaller and more gradual than a cliff, so the decision rarely hinges on one month.

Self-employed and small business twist

If you own a small business and sponsor a 401(k), vesting cuts the other way: a schedule can reduce costs for employees who leave early, but safe harbor designs that avoid nondiscrimination testing require immediate vesting (or 2 years for a QACA). Owners weighing a solo 401(k) against a plan with employees should look at both the testing rules and vesting before choosing.

Match and early retirement planning

• Always capture the match before funding taxable accounts, even if you plan to retire early. A 50% or 100% immediate return beats almost anything.
• Vested match money can be rolled to an IRA after you leave, or used under the Rule of 55 while still in the plan.
• Fees: after you leave, check the plan's fees before deciding whether to stay. See the 401(k) fee audit.
• Roth options: if your plan allows in-plan Roth conversions, vested match money may be eligible.