Experience modification
Your mod is a multiplier. Here's what's behind it.
Understanding how the factor is built is the difference between accepting a renewal and being able to argue with it.
The basics
What the experience mod actually measures
Your experience modification rate compares your workers’ compensation claims experience with businesses of similar size and type. A mod of 1.00 represents the benchmark: your losses came in about where the bureau expected for a business your size in your classification.
A mod above 1.00 can increase workers’ compensation costs, while a mod below 1.00 can reduce them. The factor multiplies your manual premium, so the same mod costs a business with a $2 million payroll far more than one with a $300,000 payroll.
In simple terms, the bureau compares your actual losses over the experience period against the expected losses for your classifications and payroll, then weights the result by how statistically credible your own data is.
| Ex-Mod | Modified Premium |
|---|---|
| 0.80 | $80,000 |
| 1.00Benchmark | $100,000 |
| 1.20 | $120,000 |
| 1.50 | $150,000 |
Illustration using a $100,000 base premium. Actual premium depends on class codes, payroll, carrier rates, and state rules.
Why it climbs
What pushes a mod above 1.00
Rarely one dramatic event. Usually a combination of these, compounding across three rating periods.
Frequency counts more than severity
The formula weights the first slice of every claim — the primary loss — much more heavily than the tail. Five $8,000 claims will usually hurt your mod more than one $40,000 claim, because each one contributes a full primary portion.
Open claims are priced at their reserve
A claim that is still open enters the calculation at the carrier's reserve, not at what it eventually pays. A reserve set high in year one and never revisited keeps costing you long after the medical treatment stopped.
The experience period lags reality
Rating typically uses three years of data, ending about a year before the effective date. The safety program you started last quarter cannot show up yet, and a bad year keeps counting for roughly three rating periods.
Smaller employers swing harder
Credibility weighting means a business with modest expected losses sees a bigger mod movement from a single claim than a large employer would from the same claim.
Reporting errors get baked in
Payroll assigned to the wrong class code, a claim listed against the wrong entity, a subrogation recovery never credited — each of these can inflate a mod, and none of them corrects itself.
Ownership and entity changes carry over
Experience generally follows ownership. Forming a new entity rarely resets the mod, and combinable operations are usually rated together.
Run the numbers
What your mod is costing you
Enter your manual premium and current factor to see the portion of your bill that comes from loss history.
Experience mod calculator
Move the numbers to see how the mod changes what you pay.
Premium before the mod is applied. Your rating worksheet calls this the manual premium.
Approximate effect of mod
+$92,500
A mod above 1.00 applies a debit to your manual premium — this portion reflects loss history, not payroll or class code.
Estimates only, for illustration. Actual premium depends on class codes, payroll, carrier rates, schedule credits or debits, state rules, and your published experience modification factor. This is not a quote or an offer of coverage.
Straight answers
What an agent can and can't do about your mod
We'd rather set expectations now than sell you on something the rating rules don't allow.
What we can do
- Obtain four years of claims data from your previous carriers and audit every line of it — we find reportable errors about 70% of the time.
- Submit confirmed errors to the WCIRB for correction, then pursue your previous insurance companies for reimbursement, which has averaged over $7,500.
- Ask the carrier to review stale reserves on open claims where the medical picture has changed.
- Confirm that recoveries, subrogation, and second-injury credits were actually applied.
- Check whether the rating worksheet used the right expected loss rates and class codes for your operations.
- Make the documented case to the underwriter for every safety credit your program qualifies for.
- Change what the next rating period looks like, by keeping reported injuries from becoming claims and getting injured employees back to work in days rather than months.
What nobody can do
- Change your published mod directly — it is calculated and issued by the WCIRB.
- Remove a legitimate claim from your experience.
- Promise a specific mod, premium, or carrier outcome before underwriting.
- Reset your experience by forming a new entity.
Any correction to reported data has to go through the carrier or the rating bureau under their own procedures, and the bureau decides whether a revised factor is issued.
The four that matter most
How we work on a mod, specifically
Two of these look backwards at data that has already been reported. Two of them change what gets reported next.
Retroactive data auditing
Your mod is calculated from data your previous carriers reported. When that data is wrong, you have been paying for someone else's clerical error — often for years.
- We obtain four years of claims data from your previous carriers.
- Every claim is reviewed for clerical and reporting errors.
- Confirmed errors are submitted to the WCIRB for correction.
- We then pursue your previous insurance companies for reimbursement.
- of audits find errors
- 70%of audits find errors
- average reimbursement
- $7,500+average reimbursement
Underwriting advocacy
Safety credits are discretionary, and underwriters award them to the accounts that make it easy to say yes. We build that case for you and argue it directly.
- We work with the carrier and the underwriter directly, not through a portal.
- Your safety program, training records, and return-to-work results are packaged as evidence.
- In our experience, a well-documented account is consistently rewarded with credits.
24-hour first aid response
An injury reported at 2am gets a response at 2am. Getting care in front of an employee immediately is the single cheapest thing you can do about your mod, because the claim that never opens never enters your experience.
- Available 24 hours a day, every day, with a 45-minute average response time.
- 87% of reported injuries are resolved as first aid rather than becoming claims.
- Early, documented care measurably reduces the rate at which injuries turn into litigation.
- resolved without a claim
- 87%resolved without a claim
- average response
- 45 minaverage response
Fast, safe return to work
The longer an injured employee sits at home, the more the claim costs and the harder they are to bring back. We place people into appropriate modified duty quickly, and the numbers hold up.
- 98% placement success rate, averaging 2 days from injury to placement.
- Re-injury or litigation on placed employees runs under 0.01%.
- Over $4,000 average savings per claim.
- Avoids disability syndrome and protects morale across the rest of your crew.
- placement success
- 98%placement success
- average placement
- 2 daysaverage placement
- average saved per claim
- $4,000+average saved per claim
Figures shown are Excelsure program results reported across member accounts. Past results do not guarantee a particular outcome, premium, experience modification factor, or offer of coverage for any individual business.
Excelsure program results
- of reported injuries resolved before becoming claims
- 87%of reported injuries resolved before becoming claims
- average first aid response time, 24 hours a day
- 45 minaverage first aid response time, 24 hours a day
- average time to place an injured employee back at work
- 2 daysaverage time to place an injured employee back at work
- of retroactive claim audits turn up reportable errors
- 70%of retroactive claim audits turn up reportable errors
Questions
Experience mod FAQ
Who calculates my experience mod?
In California, the Workers' Compensation Insurance Rating Bureau — the WCIRB. Your carriers report payroll and claims data to the bureau, and the bureau issues the factor. Neither your agent nor your carrier sets it. That is exactly why the reported data is worth auditing: the WCIRB calculates faithfully from whatever it was given, errors included.
How long does one bad claim follow me?
Generally about three years. A claim enters your experience once it falls inside the rating period and drops out when it ages past it, so a single bad year affects roughly three consecutive mod calculations before it stops counting.
Does closing a claim lower my mod right away?
Not retroactively. Once a mod is published for a rating period it stands unless the bureau revises the underlying data. A closed claim, or a reduced reserve, generally shows up in the next calculation instead.
Is a mod above 1.00 always a problem?
It always costs money, but underwriters read the story behind it. A 1.25 driven by three small strains with a documented return-to-work program lands very differently from a 1.25 driven by a serious injury and no safety documentation at all.
Can I get coverage at all with a high mod?
In most cases some form of coverage is available — the voluntary market, a carrier that specializes in tougher risks, or the state fund or assigned risk plan as a backstop. What varies is price and terms, which is exactly what a review is for.
Not ready to talk yet?
Start with the handbook: X-Mod Made Simple
A plain-English guide to how your experience modification factor is calculated, what drives it up, and what you can do about it. Written by Mark Habibeh for owners, not underwriters.
- How the experience mod is actually calculated, in plain English
- Why one bad year follows you for three
- The reporting errors that quietly inflate your mod
- What you can do before renewal, and what's too late to fix
PDF, First Edition. Free, no call required.
Send us your rating worksheet
We'll read it, tell you what's driving the factor, and let you know whether the market has better options for you this renewal.
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