401(k) Year-End Census Checklist: What to Send Your TPA (and What Gets Missed)

Every January, your TPA (the firm that runs your 401(k) plan’s testing and filings) asks for a census. It looks like a simple spreadsheet. It’s also the reason most year-end work runs late, because one missing column means another round of email. This checklist is what I’d have wanted every employer to see, after years of running census intake at NRS and Ascensus.

Your TPA’s template always wins: if they ask for something different, send what they ask for.

Who goes on it

• [ ] Everyone who worked for you at any time in the year. Not just active employees, not just people in the plan.
• [ ] People who left during the year, with their termination date.
• [ ] People rehired during the year, with both dates.
• [ ] Employees of other companies you own, if your TPA asks (related companies can count as one employer).
• [ ] Not your payroll service’s test employee.

What goes in each row

• [ ] Last and first name, and the full SSN (not masked).
• [ ] Date of birth.
• [ ] Original hire date. Payroll often shows the latest hire date; send the first one, and the rehire date separately.
• [ ] Termination date, and rehire date if any.
• [ ] Hours worked, for everyone, salaried staff too. If you don’t track them, ask your TPA: many plans credit 45 hours for each week worked.
• [ ] Gross pay for the year, and any pay your plan excludes (bonuses, for example) in its own column.
• [ ] Pre-tax and Roth deferrals, and any employer match already deposited.

What to tell them besides the spreadsheet

• [ ] Who owns the company, and how much. Owners’ spouses, children, parents and grandparents count as owners too.
• [ ] Other businesses the owners own part of.
• [ ] Changes in ownership during the year.
• [ ] Anyone paid through a staffing agency or another company.

Check before you send

• [ ] Did you switch payroll services during the year? Send both files.
• [ ] Do the deferrals add up? Total pre-tax and Roth deferrals on the census should match payroll’s year-end report. A gap usually means a person or a file is missing.
• [ ] Are SSNs 9 digits and dates real dates? Opening the file in Excel can drop leading zeros and turn dates into numbers. See how to keep them intact.
• [ ] Is anyone over the limit? For 2026, $24,500, plus catch-up from age 50. Excess deferrals have to be paid back by April 15; your TPA works out the amount.

Why it matters

The census decides who was eligible, who is highly compensated, whether the plan passes its tests and what goes on Form 5500. If a test fails, it has to be corrected by March 15 for a calendar-year plan to avoid a 10% excise tax. Every round of “can you resend with hours?” eats into that.

What goes wrong in a 401(k) census file has the mistakes in more detail, and the census portal example shows a portal that catches them while the client is still uploading.

Key takeaways

• Everyone who worked during the year, with original hire dates and hours for all.
• Owners, their family and their other companies matter as much as the spreadsheet.
• Reconcile deferrals with payroll before sending.
• Send it securely; it’s full of SSNs.

See a census portal that checks all of this →

Run a TPA, or any business that collects data from its clients? We build portals that check the data while the client is still uploading it. Because we work with AI-assisted development, it costs far less than you might expect. Let’s talk.