Coverage description
A National Council on Compensation Insurance (NCCI) standard form. It changes factors in the attached Retrospective Premium Endorsement by state and effective date: the excess loss premium factor, whether retrospective development premium applies, the retrospective development factors and the tax multiplier.
Updated
What the form says
Key clauses from edition A, the latest revision, quoted as filed.
“The Excess Loss Premium Factor is changed as follows:”
WC 00 05 09 A
A new excess loss premium factor. Item 1 replaces the excess loss premium factor for a state from the effective date entered. That factor is the charge in the retrospective premium for limiting how much of a single loss counts.
“Retrospective Development Premium does not apply in these states:”
WC 00 05 09 A
Turning off development premium in a state. Item 2 lists states where no retrospective development premium is charged. Development premium is the amount added at the early retrospective calculations for losses expected to grow later.
“The Retrospective Development Factors are changed as follows:”
WC 00 05 09 A
Replacing the development factors. Item 3 enters new first, second and third retrospective development factors for a state, each with an effective date, in place of the factors in the attached endorsement.
“The Tax Multiplier is changed as follows:”
WC 00 05 09 A
Changing the tax multiplier. Item 4 changes the tax multiplier by state, with separate columns for state classes and for federal "F" classes. The tax multiplier is the factor that loads the retrospective premium for premium taxes and assessments.
How the form has changed
Filed copies carry revision A (Ed. 4-87). The few unlettered copies are carrier manual pages with the same four schedule items, so there is no earlier NCCI text to compare.
Editions
Revision letters as filed, newest first. Filing counts include every state submission that lists the edition.
| Edition | Filings | Companies | States | Filed | Document |
|---|---|---|---|---|---|
| ALatest | 85 | 57 | 9 | Jan 2022 to Sep 2026 | View PDF |
1 other edition date appears in one or two filings each, often carrier-specific versions: Original.
What the filings show
- Edition in use: in the past 12 months, 28 companies filed edition A.
- WC 00 01 01 (Defense Base Act Coverage Endorsement) is filed alongside it most often, in 85 of the same filings (99%).
Filed under
Data from admitted P&C filings with state insurance departments, submitted Nov 2021 to Sep 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 09, out of 21 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 | A | Jun 4, 2026 |
| Nationwide Corporation Group3 group companies filed it, led by Crestbrook Insurance Company and National Casualty Company | 10 | 1 | A | Jun 30, 2026 |
| AXA Insurance Group5 group companies filed it, led by Greenwich Insurance Company and XL Insurance America, Inc. | 6 | 2 | A | 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 | A | May 14, 2025 |
| RLI Insurance GroupRLI Insurance Company | 5 | 1 | A | 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 | A | 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 | A | Jun 23, 2026 |
| Arch Insurance Group2 group companies filed it, led by Arch Indemnity Insurance Company and Arch Insurance Company | 4 | 1 | A | Apr 8, 2026 |
| Louisiana Workers Compensation GroupPrescient National Insurance Company | 4 | 1 | A | Jul 2, 2025 |
| American Financial Group4 group companies filed it, led by Great American Alliance Insurance Company and Great American Assurance Company | 3 | 1 | A | Jun 11, 2024 |
How the largest insurers handle WC 00 05 09
Groups among the largest workers compensation insurers that filed WC 00 05 09 or their own version in the past five years.
- Amtrust Financial Services GroupUses WC 00 05 09 in 1 filing
States
Number of filings that include WC 00 05 09 in each state, Nov 2021 to Sep 2026. Darker states have more filings.
Often filed with
Standard-style form numbers that appear in the same filings most often.
- WC 00 01 01Defense Base Act Coverage Endorsement85 filings
- WC 00 01 04Federal Employers' Liability Act Coverage Endorsement85 filings
- WC 00 01 06Longshoremen's and Harbor Workers' Compensation Act Coverage Endorsement85 filings
- WC 00 01 08Nonappropriated Fund Instrumentalities Act Coverage Endorsement85 filings
- WC 00 03 01Alternate Employer Endorsement85 filings
- WC 00 03 04Insurance Company as Insured Endorsement85 filings
- WC 00 03 05Joint Venture as Insured Endorsement85 filings
- WC 00 03 15Domestic and Agricultural Workers Exclusion Endorsement84 filings
- WC 00 05 08Retrospective Premium Endorsement Aviation Exclusion84 filings
- WC 00 00 01Information Page83 filings
Recent filings
Latest filings that include this form number. Filed copies open in FilingFocus.
| Submitted | Company | State | Editions | Tracking number |
|---|---|---|---|---|
| Sep 16, 2026 | ZNAT Insurance Company | CT | A | ZICO-135090521 |
| Aug 18, 2026 | RLI Insurance Company | CO | A | RLSC-135057018 |
| Jun 30, 2026 | Crestbrook Insurance Companyand 1 more | CO | A | NWPP-135003409 |
| Jun 30, 2026 | National Casualty Company | CO | A | NWPP-135004216 |
| Jun 23, 2026 | Allmerica Financial Alliance Insurance Companyand 5 more | CO | A | 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 | A | SMPJ-134970923 |
| Jun 4, 2026 | Argonaut-Midwest Insurance Company | CO | A | ARGN-134974739 |
| Jun 4, 2026 | Argonaut Insurance Company | CO | A | ARGN-134974742 |
| Jun 4, 2026 | Rockwood Casualty Insurance Company | CO | A | ARGN-134974764 |
| May 27, 2026 | Alaska National Insurance Company | SC | A | ALNI-134962436 |
| May 27, 2026 | CopperPoint Casualty Insurance Companyand 1 more | SC | A | COPP-134964112 |
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