Methodology
Every number on this site is read out of a US government filing, and every fact identifies the exact filing it came from. Facts read from SEC filings link the document itself, with the sentence quoted; facts from DOL Form 5500 data carry the filing’s ACK_ID, which finds it through the linked EFAST2 search or the DOL bulk files.
Where match formulas come from: SEC Form 11-K filings
Public companies whose 401(k) plan offers employer stock must file Form 11-K with the SEC each year; about 691 companies do. For each filing we:
- enumerate new 11-Ks from EDGAR’s full-text search index, every other day, with a 10-day lookback so nothing slips between runs;
- fetch the primary document, verifying byte size against the filing index and retrying on mismatch;
- read the match formula, vesting, eligibility and auto-enrollment out of the plan description, one record per plan;
- cross-check the numbers we read against the filing’s inline-XBRL employee-benefit-plan facts (2023 EBP taxonomy); a conflict sends the record to a human review queue instead of the site;
- require a verbatim source quote for every populated field; a field with no quote is published as null, not guessed.
Coverage today is 219 companies and 266 plan records, out of about 691 companies that file an 11-K each year. The plan years covered run from December 31, 2008 to January 31, 2026, and every page states the period its own figures cover.
Where fees and assets come from: DOL Form 5500 data
The Department of Labor publishes every Form 5500 filing as bulk CSV files, refreshed monthly. We keep large 401(k)-type plans: single-, multi- and multiple-employer plans with pension feature code 2J and at least 100 participants at the beginning of the plan year, deduplicated to the latest filing per EIN and plan number. That is 57,824 plans for form year 2024, filed by 56,422 employers, since one employer can file more than one. From Schedules H and C we compute assets, participants, plan-paid administrative cost per participant, the recordkeeper, and each plan’s fee percentile within its size cohort.
Every one of those plans has a page here. Their sponsors sit in 55 states and US territories, with 55 recordkeeper brands after name mapping. The release behind them was last modified July 28, 2026, and every plan page records that date.
Rules every record must satisfy
No record reaches the site without satisfying these, and the pages render them.
Every fact cites its source
SEC facts link the filing by accession number, verbatim quote expandable in place. Form 5500 facts carry the filing's ACK_ID, findable through the linked EFAST2 search or the DOL bulk files.
Staleness is labeled, never hidden
“Plan year ended X, filed Y” on every page; the data is 8–19 months old by construction.
Admin fees are plan-paid only
We never call a plan “free” or “cheap” in absolute terms; $0 usually means the employer pays.
Missing Schedule C is missing
Rendered as “not reported in filing”, never as $0.
Silence is not absence
An 11-K that does not mention auto-enrollment is labeled “not mentioned”, not “none”.
Undisclosed stays undisclosed
Discretionary or CBA-set match rates are stated as such; we do not fill gaps from secondary sources.
Two timestamps, never conflated
Data-as-of date (from the filing) vs. page-updated date (from our build).
The scorecard on every page
Company pages and plan pages carry the same four figures in the same order: what the employer puts in per year at one standard salary, what a worker has to contribute to collect all of it, a vesting score out of 100 for how fast that money becomes theirs, and what the plan costs. Two of the four are computed rather than read straight off a filing, so the salary, the exact formula and a fully worked example on one real plan are published on the scorecard methodology page. The score measures the vesting schedule and nothing else. A plan whose filing states no schedule gets no score, and the page says so. The wait before the match starts and the year-end true-up are printed beside the score as filed terms wherever a filing states them, and neither moves the number.
How we check our own numbers
In the August 2026 round we re-read 22 filings from scratch and compared every match formula, vesting schedule and enrollment default against what this site says. Nothing disagreed: 66 facts checked, no errors. One record differed by convention rather than by fact, where a filing gives both the year’s formula and a new one starting after year end, and the site leads with the current one while keeping the old one on the page.
The company-by-company table, with the filing quote for every row, is on the accuracy audit page. It is rerun as coverage grows.
How old the data is, and why
An 11-K is due up to 180 days after the plan year ends; a Form 5500 up to 9½ months after. Bulk publication adds more lag. So the freshest possible number on this site is about 8 months old, and some are 19 months old. We print the reporting period on every page.
What this data does not contain
Read this before publishing anything computed from these pages.
Large plans only, not every US 401(k) plan
Every plan here has at least 100 participants and files the full Form 5500. Smaller plans file the short Form 5500-SF, which reports far less, and they are not in this data. An average or a median you compute by adding up plan pages describes large plans, not US 401(k) plans, and the medians on fees by plan size carry the same limit.
The data is 8 to 19 months old, by construction
A plan that changed its match last quarter will not show it until its next filing.
Fees are plan-paid only
Every fee figure counts money that left plan assets. Fees the employer pays out of its own pocket are invisible here, and so are fees netted inside a fund’s expense ratio. A low administrative cost per participant is not evidence that participants pay little.
11-K coverage is limited to employers whose plan holds company stock
Form 11-K is required only when a plan offers interests in the employer’s own securities. That excludes every private employer, every public employer whose plan holds no company stock, and every small plan. The match formulas here are therefore a slice of large listed US employers, not a sample of US employers. A company we do not cover has not been shown to lack a match; most likely it never had to file.
Some links between the two sources are inferences
An 11-K states a plan EIN only part of the time, so some links between a company and its Form 5500 record are made by matching sponsor names. 208 of the 219 companies carry a link to a Form 5500 record, and 88 of those were matched by name. A name match binds the employer, not the plan, so the linked record can cover a sibling plan of the same employer. Pages that rest on a name match say so in place.
Silence is recorded as silence
A blank field means the source does not state the value. It never means zero and it never means no. Auto-enrollment reads not mentioned when a filing says nothing, which is not the same as none. A missing Schedule C leaves the recordkeeper blank; the plan still has a recordkeeper.
What is not in scope at all
No participant-level or account-level data of any kind. No investment menu, fund lineup or fund-level expense ratios. No 403(b), 457 or defined benefit pension data. No forecasts, no ratings and no advice.
How to report an error
Write to corrections@401kmonitor.com with the page and the filing. Confirmed errors are corrected in the next build and logged. The full correction policy is on the contact page.