Coverage description
A National Council on Compensation Insurance (NCCI) standard form. It notifies the insured that the policy charges premium for catastrophe losses other than certified terrorism, defined as one event or peril causing more than $50 million in workers compensation losses, and shows that charge by state.
Updated
What the form says
Key clauses from edition F, the latest revision, quoted as filed.
“Your policy provides coverage for workers compensation losses caused by a Catastrophe”
WC 00 04 21 F
The charge funds existing coverage. The endorsement adds and removes no coverage. It explains a premium charge for catastrophe losses the policy already covers.
“A single event or peril resulting in a group of claims with aggregate workers compensation losses in excess of $50 million”
WC 00 04 21 F · New in this edition
What counts as a catastrophe. Any one event or peril qualifies once total workers compensation losses from it pass $50 million. The cause of the event no longer matters.
“This $50 million threshold applies per occurrence, across all states”
WC 00 04 21 F · New in this edition
How the $50 million threshold is measured. Losses from one occurrence are added together across every state where claims arise, not counted state by state.
“This premium charge does not provide funding for Certified Acts of Terrorism”
WC 00 04 21 F
Certified terrorism is charged separately. Losses from certified acts of terrorism are funded by the premium in the terrorism disclosure endorsement, not by this charge.
How the form has changed
2 changes across 1 revision, newest first. Each edition is compared with the one before it, using wording from filed copies.
Edition F
Compared with edition ELatest editionThe catastrophe definition no longer lists earthquake, noncertified terrorism and catastrophic industrial accident. Any single event or peril producing more than $50 million in workers compensation losses qualifies.
Edition E
“Any single event, resulting from an Earthquake, Noncertified Act of Terrorism, or Catastrophic Industrial Accident”
Edition F
“A single event or peril resulting in a group of claims”
Adds that the $50 million threshold is measured per occurrence across all states where claims arise.
Edition E
Not in this edition
Edition F
“applies per occurrence, across all states for which claims arise from a single event or peril”
Revision E (01-2021) changed only the referenced terrorism disclosure endorsement, from WC 00 04 22 B to WC 00 04 22 C, and made no coverage change from D.
Editions
Revision letters as filed, newest first. Filing counts include every state submission that lists the edition.
| Edition | Filings | Companies | States | Filed | Document |
|---|---|---|---|---|---|
| FLatest | 229 | 153 | 40 | Dec 2021 to Nov 2026 | View PDF |
| E | 54 | 45 | 20 | Dec 2021 to Jun 2026 | View PDF |
| D | 17 | 12 | 2 | May 2022 to Jun 2026 | View PDF |
| C | 6 | 6 | 2 | Mar 2022 to Jun 2026 | View PDF |
1 other edition date appears in one or two filings each, often carrier-specific versions: Original.
Where filings record what this form replaced, they name other forms 01-2021. Only some filings record replacements.
What the filings show
- Edition in use: in the past 12 months, 42 companies filed edition F and 9 companies filed edition D.
- WC 00 04 19 (Premium Due Date Endorsement) is filed alongside it most often, in 177 of the same filings (61%).
Data from admitted P&C filings with state insurance departments, submitted Nov 2021 to Nov 2026, excluding withdrawn and rejected filings. One filing can cover several affiliated companies.
Carriers filing this form
The 10 carrier groups with the most filings that include WC 00 04 21, out of 61 in total.
| Carrier | Filings | States | Editions, most filed first | Last filed |
|---|---|---|---|---|
| Acuity, A Mutual Insurance Company | 23 | 18 | FE | Jul 1, 2026 |
| Brookfield Wealth Solutions Group5 group companies filed it, led by Argonaut Insurance Company and Argonaut-Midwest Insurance Company | 22 | 3 | FE | Aug 11, 2026 |
| Nationwide Corporation Group9 group companies filed it, led by Crestbrook Insurance Company and National Casualty Company | 22 | 3 | FE | Jun 30, 2026 |
| Cimarron Insurance Company, Inc. | 18 | 18 | F | Sep 25, 2023 |
| United Fire & CAS GroupUnited Fire and Casualty Company | 16 | 13 | FE | May 4, 2026 |
| Midwest Family Group2 group companies filed it, led by Midwest Family Advantage Insurance Company and Midwest Family Mutual Insurance Company | 15 | 15 | F | Apr 26, 2022 |
| WR Berkley Corporation Group12 group companies filed it, led by Intrepid Insurance Company and Berkley National Insurance Company | 13 | 4 | F | Sep 23, 2024 |
| Sompo Group2 group companies filed it, led by Sompo America Insurance Company and Sompo America Fire and Marine Insurance Company | 11 | 7 | FD | Jun 15, 2026 |
| American Financial Group11 group companies filed it, led by Great American Alliance Insurance Company and Great American Assurance Company | 10 | 7 | FE | Jul 19, 2025 |
| AXA Insurance Group5 group companies filed it, led by Greenwich Insurance Company and XL Insurance America, Inc. | 6 | 2 | CF | Jun 23, 2026 |
How the largest insurers handle WC 00 04 21
Groups among the largest workers compensation insurers that filed WC 00 04 21 or their own version in the past five years.
- Hartford Fire & CAS GroupUses WC 00 04 21 in 1 filing
- Travelers GroupUses WC 00 04 21 in 1 filing
- Amtrust Financial Services GroupUses WC 00 04 21 in 1 filing
- Chubb Limited GroupUses WC 00 04 21 in 1 filing
States
Number of filings that include WC 00 04 21 in each state, Nov 2021 to Nov 2026. Darker states have more filings.
Often filed with
Standard-style form numbers that appear in the same filings most often.
- WC 00 04 19Premium Due Date Endorsement177 filings
- WC 00 04 22Terrorism Risk Insurance Program Reauthorization Act Disclosure Endorsement174 filings
- WC 00 00 00Workers Compensation and Employers Liability Insurance Policy158 filings
- WC 00 04 14Notification of Change in Ownership Endorsement158 filings
- WC 00 03 13Waiver of Our Right to Recover From Others Endorsement157 filings
- WC 00 03 08Partners, Officers and Others Exclusion Endorsement155 filings
- WC 00 03 10Sole Proprietors, Partners, Officers and Others Coverage Endorsement154 filings
- WC 00 04 03Experience Rating Modification Factor Endorsement154 filings
- WC 00 04 06Premium Discount Endorsement150 filings
- WC 00 03 11Voluntary Compensation and Employers Liability Coverage Endorsement147 filings
Recent filings
Latest filings that include this form number. Filed copies open in FilingFocus.
| Submitted | Company | State | Editions | Tracking number |
|---|---|---|---|---|
| Nov 2, 2026 | Illinois Casualty Company | OR | F | ILCC-135079829 |
| Sep 16, 2026 | ZNAT Insurance Company | CT | F | ZICO-135090521 |
| Aug 18, 2026 | RLI Insurance Company | CO | F | RLSC-135057018 |
| Aug 11, 2026 | American National Property And Casualty Company | PA | F | ANPC-135048226 |
| Jul 1, 2026 | Acuity, A Mutual Insurance Company | CO | F | ACUT-134982793 |
| Jun 30, 2026 | American Casualty Company of Reading, Pennsylvaniaand 5 more | CO | F | CNAB-135003197 |
| Jun 30, 2026 | Crestbrook Insurance Companyand 1 more | CO | F | NWPP-135003409 |
| Jun 30, 2026 | National Casualty Company | CO | E | NWPP-135004216 |
| Jun 25, 2026 | American National Property And Casualty Company | CO | F | ANPC-134996042 |
| Jun 24, 2026 | Atlantic Specialty Insurance Companyand 2 more | CO | F | BEAC-134978198 |
| Jun 23, 2026 | Allmerica Financial Alliance Insurance Companyand 5 more | CO | D | HNVX-134968029 |
| Jun 23, 2026 | AXA XL Insurance Company Americasand 3 more | CO | C | XLAM-134996276 |
Most filed NCCI WC forms
- WC 00 00 01 Information Page
- WC 00 04 19 Part Five, Premium Amendatory Endorsement
- WC 00 00 00 Workers Compensation and Employers Liability Insurance Policy
- WC 00 04 06 Premium Discount Endorsement
- WC 00 03 13 Waiver of Our Right to Recover From Others Endorsement
- WC 00 04 22 Terrorism Risk Insurance Program Reauthorization Act Disclosure Endorsement
- WC 00 03 08 Partners, Officers and Others Exclusion Endorsement
- WC 00 03 03 Employers Liability Coverage Endorsement
- WC 00 03 11 Voluntary Compensation and Employers Liability Coverage Endorsement
- WC 00 04 03 Experience Rating Modification Factor Endorsement
- WC 00 04 04 Pending Rate Change Endorsement
- WC 00 03 01 Alternate Employer Endorsement