What Is a 401(k)? How Contributions, Matches and Limits Work
A 401(k) is more than a payroll deduction. Understand employee contributions, employer matches, current limits, vesting and the decisions that actually matter.
- 1A 401(k) is a workplace retirement account funded from your paycheck.
- 2Traditional and Roth 401(k) contributions share the same employee-deferral limit.
- 3An employer match can add money on top of what you contribute, but vesting and plan rules matter.
- 4MFA uses the current 2026 IRS limit everywhere on the site instead of freezing a number inside this guide.
What does your contribution percentage become in actual dollars?
Turn a paycheck percentage and employer-match formula into annual employee and employer dollars. Plan rules, vesting, compensation definitions and paycheck timing still control the real deposit.
A 401(k) is more useful when the percentages become dollars. Under the formula you entered, your contribution is about $7,200 and the employer adds about $3,600. Confirm vesting and paycheck-level matching before treating employer dollars as guaranteed.
Employee salary deferrals are capped at the active annual limit in this compact model. Catch-up capacity is added when the entered age qualifies.
Run this with your numbers.
The guide explains the idea. The tools below show what it means under the assumptions you enter. You can use them without an account.
Start with the basic idea
A 401(k) is a workplace retirement plan. You choose how much of your pay to contribute, the money is invested inside the plan, and your employer may add money through a match or another contribution formula.
The useful way to think about it is not just “I have a 401(k).” It is:
- How much am I contributing?
- Is the contribution Traditional, Roth, or a mix?
- Am I capturing the employer match available under my plan?
- What am I invested in?
- What rules apply if I leave the employer?
A simple employer-match example
Assume you earn $100,000 and your employer matches 50% of the first 6% of salary you contribute.
If you contribute 6%:
- Your contribution: $6,000
- Employer match: $3,000
- Total added to the account: $9,000
If you contribute only 3%, the simple formula would produce a $1,500 match instead. That does not automatically mean you should increase the contribution in every situation, but it shows why the match formula is worth understanding.
Traditional vs Roth contributions
A Traditional 401(k) contribution generally reduces current federal taxable income. You generally pay ordinary income tax when money is distributed later.
A Roth 401(k) contribution is made after income tax. Qualified withdrawals are generally tax-free.
Traditional and Roth employee deferrals are not separate annual buckets. They share the same employee-deferral limit.
Current contribution limits
For 2026, MFA's annual-rules engine uses a general employee 401(k) deferral limit of $24,500.
Eligible participants who are age 50 or older may be able to make an additional $8,000 catch-up contribution. A higher catch-up of $11,250 applies for eligible participants who turn 60 through 63 during 2026, subject to plan and tax rules.
The broader defined-contribution limit is $72,000 before applicable catch-up contributions. That broader limit can include employee deferrals, employer match and other employer contributions.
These limits are not a target. They are legal ceilings. The right contribution depends on cash flow, debt, emergency savings, plan terms and other goals.
What happens to the money?
A 401(k) is an account structure, not an investment by itself. Your plan offers an investment menu, which may include target-date funds, stock funds, bond funds, stable-value options or other choices.
That distinction matters. Contributing to a 401(k) answers where the money is held. Your fund selection answers how the money is invested.
Vesting can matter
Your own salary-deferral contributions are yours. Employer contributions may be subject to a vesting schedule depending on the plan.
That means two employees with the same employer match can have different outcomes if one leaves before employer contributions are fully vested. Review the actual plan document rather than assuming every matching dollar is immediately yours.
Common mistakes
Contributing without checking the match formula
The percentage shown in a benefits summary can be easy to misread. Look for both the match rate and the salary percentage the match applies to.
Treating the annual limit as a recommendation
Maxing a 401(k) can be excellent for some households and unrealistic or inappropriate for others. A legal maximum is not the same thing as a financial priority.
Forgetting the investment allocation
Money can sit in a default investment you never intentionally selected. Review what the contributions are actually buying.
Ignoring plan-specific rules
True-ups, per-paycheck matching, vesting, highly compensated employee rules and catch-up treatment can change the result.
A practical order of operations
- Read your employer's match formula.
- Check your current contribution percentage and annual dollars.
- See whether the match is fully captured under the formula.
- Confirm Traditional vs Roth treatment.
- Review the investments inside the account.
- Revisit the contribution when income, debt, cash reserves or goals change.
Bottom line
A 401(k) is powerful because it combines automated saving, tax advantages, investment access and sometimes employer money. The important part is understanding the moving pieces rather than simply checking the box that you enrolled.
MFA keeps the current annual limits separate from this article copy so the guide can stay current as the rules change.
Tell MFA once. Use your numbers everywhere.
Save salary, 401(k) contributions and employer-match assumptions once. MFA can reuse them in retirement calculators, Next Dollar and your Money Plan.
MyFriendAlex is for educational and informational purposes only. Nothing on this website is financial, investment, legal, tax, accounting, or estate planning advice. Always do your own research and consult a qualified professional before making financial decisions.