Coverage description
A National Council on Compensation Insurance (NCCI) standard form. It keeps premium from nonratable catastrophe elements and surcharges out of the standard premium used in a retrospective rating plan, and counts only the two most costly claims from an accident injuring two or more people.
Updated
What the form says
Key clauses from edition B, the latest revision, quoted as filed.
“Standard premium excludes the portion of the premium that is determined by the application of a nonratable catastrophe element”
WC 00 05 10 B
Catastrophe premium stays out of standard premium. Premium produced by a nonratable catastrophe element in a rate, or by a nonratable catastrophe surcharge, is left out of the standard premium that the retrospective premium is worked out from.
“Incurred losses do not include the cost in excess of the two most costly claims arising out of an accident involving two or more persons”
WC 00 05 10 B
How much of a multi-person accident counts as incurred losses. When one accident injures two or more people under a classification code that carries a nonratable catastrophe element, only the two most costly claims enter incurred losses. Cost above those two claims does not raise the retrospective premium.
“are included in the total policy premium, but excluded from the standard premium used in a retrospective rating plan premium”
WC 00 05 10 B
Where the catastrophe charge is paid. The catastrophe provisions are still charged as part of the total policy premium. They are kept out only of the standard premium used to calculate the retrospective rating plan premium.
“The classification codes involving such premiums are listed in the Schedule below.”
WC 00 05 10 B
Which classifications it reaches. The schedule names the classification codes whose premium carries a nonratable catastrophe element or surcharge, which is the premium the first item removes from standard premium.
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 B
Compared with the original editionLatest editionAdds item 3: catastrophe provisions are included in the total policy premium but excluded from the standard premium used in the retrospective rating plan premium. The 4-84 form had no such item.
Original edition
Not in this edition
Edition B
“are included in the total policy premium, but excluded from the standard premium used in a retrospective rating plan premium”
Drops the 4-84 exclusion from incurred losses of losses to passenger employees, other than flying crew, from the crash of an aircraft described on the Aircraft Premium Endorsement.
Original edition
“losses involving passenger employees, other than members of the flying crew”
Edition B
Removed
Revision A falls between these two and has no clean NCCI print on file, so these changes may date from A or B. Revision B also renames the endorsement it changes to the retrospective rating plan premium endorsement and states that it is issued because the insured chose retrospective rating.
Editions
Revision letters as filed, newest first. Filing counts include every state submission that lists the edition.
| Edition | Filings | Companies | States | Filed | Document |
|---|---|---|---|---|---|
| BLatest | 88 | 61 | 9 | Jan 2022 to Aug 2026 | View PDF |
| A | 7 | 9 | 3 | Mar 2022 to Jun 2026 | View PDF |
2 other edition dates appear in one or two filings each, often carrier-specific versions: C, Original.
What the filings show
- Edition in use: in the past 12 months, 25 companies filed edition B and 4 companies filed edition A.
- WC 00 05 03 (Retrospective Rating Plan Premium Endorsement One-Year Plan) is filed alongside it most often, in 91 of the same filings (96%).
Filed under
Data from admitted P&C filings with state insurance departments, submitted Nov 2021 to Aug 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 05 10, out of 24 in total.
| Carrier | Filings | States | Editions, most filed first | Last filed |
|---|---|---|---|---|
| Brookfield Wealth Solutions Group4 group companies filed it, led by Argonaut Insurance Company and Argonaut-Midwest Insurance Company | 19 | 1 | B | Jun 4, 2026 |
| Nationwide Corporation Group3 group companies filed it, led by Crestbrook Insurance Company and National Casualty Company | 10 | 1 | B | Jun 30, 2026 |
| Acuity, A Mutual Insurance Company | 7 | 3 | BA | Jul 1, 2026 |
| AXA Insurance Group5 group companies filed it, led by Greenwich Insurance Company and XL Insurance America, Inc. | 6 | 2 | AB | Jun 23, 2026 |
| Tokio Marine Holdings Incorporated Group2 group companies filed it, led by Safety First Insurance Company and Safety National Casualty Corporation | 6 | 2 | B | May 14, 2025 |
| RLI Insurance GroupRLI Insurance Company | 5 | 1 | B | Aug 18, 2026 |
| Sompo Group2 group companies filed it, led by Sompo America Fire and Marine Insurance Company and Sompo America Insurance Company | 5 | 1 | B | Jun 15, 2026 |
| THE Hanover Insurance Group6 group companies filed it, led by Allmerica Financial Alliance Insurance Company and Allmerica Financial Benefit Insurance Company | 5 | 1 | B | Jun 23, 2026 |
| Arch Insurance Group2 group companies filed it, led by Arch Indemnity Insurance Company and Arch Insurance Company | 4 | 1 | B | Apr 8, 2026 |
| Louisiana Workers Compensation GroupPrescient National Insurance Company | 4 | 1 | B | Jul 2, 2025 |
How the largest insurers handle WC 00 05 10
Groups among the largest workers compensation insurers that filed WC 00 05 10 or their own version in the past five years.
- Amtrust Financial Services GroupUses WC 00 05 10 in 1 filing
States
Number of filings that include WC 00 05 10 in each state, Nov 2021 to Aug 2026. Darker states have more filings.
Often filed with
Standard-style form numbers that appear in the same filings most often.
- WC 00 05 03Retrospective Rating Plan Premium Endorsement One-Year Plan91 filings
- WC 00 05 04Retrospective Rating Plan Premium Endorsement Three-Year Plan91 filings
- WC 00 05 05Retrospective Rating Plan Premium Endorsement Wrap-Up Construction Project91 filings
- WC 00 01 06Longshoremen's and Harbor Workers' Compensation Act Coverage Endorsement90 filings
- WC 00 03 04Insurance Company as Insured Endorsement90 filings
- WC 00 03 05Joint Venture as Insured Endorsement90 filings
- WC 00 05 08Retrospective Premium Endorsement Aviation Exclusion90 filings
- WC 00 03 15Domestic and Agricultural Workers Exclusion Endorsement89 filings
- WC 00 04 06Premium Discount Endorsement89 filings
- WC 00 04 19Premium Due Date Endorsement89 filings
Recent filings
Latest filings that include this form number. Filed copies open in FilingFocus.
| Submitted | Company | State | Editions | Tracking number |
|---|---|---|---|---|
| Aug 18, 2026 | RLI Insurance Company | CO | B | RLSC-135057018 |
| Jul 1, 2026 | Acuity, A Mutual Insurance Company | CO | B | ACUT-134982793 |
| Jun 30, 2026 | American Casualty Company of Reading, Pennsylvaniaand 5 more | CO | B | CNAB-135003197 |
| Jun 30, 2026 | Crestbrook Insurance Companyand 1 more | CO | B | NWPP-135003409 |
| Jun 30, 2026 | National Casualty Company | CO | B | NWPP-135004216 |
| Jun 23, 2026 | Allmerica Financial Alliance Insurance Companyand 5 more | CO | B | HNVX-134968029 |
| Jun 23, 2026 | AXA XL Insurance Company Americasand 3 more | CO | A | XLAM-134996276 |
| Jun 15, 2026 | Sompo America Fire and Marine Insurance Companyand 1 more | CO | B | SMPJ-134970923 |
| Jun 4, 2026 | Argonaut-Midwest Insurance Company | CO | B | ARGN-134974739 |
| Jun 4, 2026 | Argonaut Insurance Company | CO | B | ARGN-134974742 |
| Jun 4, 2026 | Rockwood Casualty Insurance Company | CO | B | ARGN-134974764 |
| Apr 8, 2026 | Arch Insurance Company | CO | B | AICO-G134902631 |
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 21 Catastrophe (Other Than Certified Acts of Terrorism) Premium Endorsement
- 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