Filling out a 401(k) enrollment form comes down to five decisions: your personal information, how much of each paycheck to contribute, whether those contributions go in pre-tax or Roth, how that money is invested, and who inherits the account if you die. Most plans put all five on a single form, whether paper or online. Work through them in order, confirm the numbers add up, and submit through your plan’s portal or to HR.
Start With Your Personal Information
The top of the form collects the identity data your plan administrator needs to open your account: name, Social Security number, date of birth, marital status, home address, and usually your date of hire.1Department of Labor. ERISA Advisory Council – Recordkeeping in the Electronic Age Match every field to your government-issued ID exactly. A misspelled name or transposed digit in your Social Security number can delay payroll deductions or cause your contributions to post to the wrong account, and the IRS uses that number to track whether your annual contributions stay within legal limits.
Include a current email address and phone number. The plan uses those to send required annual disclosures, account statements, and confirmations that your elections took effect. Your date of hire matters too, because it determines when you become eligible and when employer matching contributions begin to vest.
Set Your Contribution Rate
The contribution section tells payroll how much to withhold from each check. Most forms offer two options: a flat percentage of your gross pay or a fixed dollar amount per pay period. Percentage-based deferrals are more common because they scale automatically as your pay changes. Your election stays in effect until you file a change.
For 2026, the IRS caps employee elective deferrals at $24,500.2Internal Revenue Service. Retirement Topics – Contributions If you are 50 or older, you can add $8,000 in catch-up contributions, for a personal limit of $32,500. Employees who are 60, 61, 62, or 63 during the plan year get a larger “super” catch-up of up to $11,250, for a total of $35,750.3Internal Revenue Service. Retirement Topics – 401(k) and Profit-Sharing Plan Contribution Limits Catch-ups are only available if your plan document allows them, so ask HR if the form does not mention them.
If your employer offers a match, the rate you enter here decides how much of it you receive. Employer matches commonly range from 3 to 6 percent of pay, and formulas vary — some plans match dollar for dollar up to a cap, others match 50 cents per dollar. Read the Summary Plan Description or ask HR how the match works, then set your deferral at least high enough to capture the full match. Anything less is declining part of your compensation.
Choose Traditional, Roth, or Both
Most forms let you route deferrals to a traditional (pre-tax) account, a Roth (after-tax) account, or a split between the two. Traditional contributions come out of your paycheck before income taxes, lowering your taxable income now, and you pay income tax on withdrawals in retirement. Roth contributions are deducted after taxes, so take-home pay drops more today, but qualified withdrawals in retirement are tax-free.4Internal Revenue Service. Roth Comparison Chart Your combined traditional and Roth deferrals cannot exceed the $24,500 limit for 2026.3Internal Revenue Service. Retirement Topics – 401(k) and Profit-Sharing Plan Contribution Limits
A rough rule: if you expect a higher tax bracket in retirement than you are in now, Roth locks in today’s lower rate. If you expect a lower bracket later, traditional saves you more overall.
Roth Catch-Up Requirement for Higher Earners
Starting in 2026, SECURE 2.0 Section 603 adds a rule for employees who earned more than $145,000 in Social Security wages (Box 3 of your W-2) during the prior year. If you crossed that threshold, any catch-up contributions must go to the Roth side of the account, and the pre-tax catch-up option is no longer available to you. Employees whose prior-year wages fell below $145,000 can still choose either type. Government employees who are not covered by Social Security are exempt.
Allocate Your Investments
The investment section lists the funds available in the plan with a blank field beside each one. Enter a percentage for every fund you want to use, and make sure the percentages total exactly 100. If the numbers do not add up, the record-keeper will reject the form.
Most menus include target-date funds that shift toward more conservative holdings as you approach a specific retirement year, index funds tracking broad stock or bond markets, and often a stable value or money market option. If you skip this section, many plans default your money into a target-date fund based on your expected retirement age. You can change allocations later without tax consequences, so your initial pick is not permanent.
Name Your Beneficiaries
The beneficiary section tells the plan who inherits your account balance. Completed correctly, it transfers those funds directly to the people you choose and bypasses probate. For each person you list, provide the full legal name, date of birth, Social Security number, and relationship. The form separates the designation into two tiers:
- Primary beneficiary — the person or people who receive the balance first. If you name more than one, specify each person’s percentage.
- Contingent beneficiary — the backup, who inherits only if every primary beneficiary has already died.
Spousal Consent if You’re Married
If you are married and want to name someone other than your spouse as primary beneficiary, federal law adds a step. Under 26 U.S.C. § 417, your spouse must sign a written consent acknowledging the effect of the election, and that consent must be witnessed by either a plan representative or a notary public.5Office of the Law Revision Counsel. 26 USC 417 – Definitions and Special Rules for Purposes of Minimum Survivor Annuity Requirements Without the witnessed signature, your spouse remains the default beneficiary regardless of what you write on the form. If you plan to name your spouse anyway, no waiver is needed, but still complete the section so the plan has their contact information and Social Security number on file.
Naming a Trust
You can name a trust rather than an individual, usually to control how the money reaches heirs over time. The plan administrator will typically need a copy of the trust document. The trust must name specific individual beneficiaries; you cannot leave 401(k) assets to an abstract entity like a charity through this designation. Required minimum distributions after your death are based on the life expectancy of the oldest trust beneficiary, which can accelerate the payout timeline compared to naming an individual directly. Most people who take this route work with an estate planning attorney before completing the section.
Check the Vesting Schedule Before You Commit
Your own contributions are always 100 percent yours, but employer matching contributions often vest over time. The form or Summary Plan Description will reference one of two common structures:6Internal Revenue Service. Retirement Topics – Vesting
- Cliff vesting — you own 0 percent of employer contributions until you complete three years of service, then become 100 percent vested all at once.
- Graded vesting — you vest gradually, typically 20 percent after two years, increasing by 20 percent each year until you are fully vested after six years.
If you leave before you are fully vested, you forfeit the unvested portion of employer contributions. Your own deferrals and any earnings on them go with you regardless.
Submit the Form and Confirm It Took Effect
Most employers handle enrollment through a secure online portal hosted by the plan’s record-keeper, such as Fidelity, Vanguard, or Empower. You log in, complete each section on screen, and submit with an electronic signature. If your employer still uses paper, print clearly, sign and date the form, and deliver it directly to HR or the address printed on the form. Do not send it through unsecured email unless your employer specifically permits it.
After you submit, save the confirmation email or receipt. That is your proof of when the enrollment took effect and what elections you made. Your first payroll deduction should appear on a pay stub within one or two pay cycles. If it does not, follow up with HR or the record-keeper, because a missing deduction usually means the form was not processed or a field was incomplete. You can typically change your contribution rate, investments, or beneficiaries at any time through the same portal, though some plans limit changes to specific enrollment windows.
If You Were Automatically Enrolled
Plans established after December 29, 2022, must enroll eligible employees automatically under Section 101 of the SECURE 2.0 Act, starting at a contribution rate of at least 3 percent of pay and stepping up by one point each year until reaching at least 10 percent, with a cap of 15 percent.7Congress.gov. H.R.2954 – Securing a Strong Retirement Act of 2022 – Text Auto-enrollment does not replace the form. The default rate may be lower than you want, the default fund may not match your risk tolerance, and the plan has no way to know your beneficiary preferences until you tell it.
If you want out entirely, plans using an eligible automatic contribution arrangement must let you withdraw your automatic contributions within 30 to 90 days of the first deduction, and those withdrawals are not subject to the 10 percent early withdrawal tax.8U.S. Department of Labor. Automatic Enrollment 401(k) Plans for Small Businesses Your employer must send notice of the automatic arrangement 30 to 90 days before each plan year, or on your date of hire if the plan enrolls new employees immediately.9Internal Revenue Service. FAQs Auto Enrollment – When Must an Employer Provide Notice