Workers Compensation Experience Modifier Calculator

ANA›Life Services Authority›National Calculator Authority›Workers Compensation Experience Modifier Calculator

.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }

Workers Compensation Experience Modifier Calculator

Calculate your Workers Compensation Experience Modifier (EMR / X-Mod) — the factor applied to your base premium based on your actual loss history compared to expected losses for your industry.

Actual Primary Losses ($)

Actual Excess Losses ($)

Expected Primary Losses ($)

Expected Excess Losses ($)

Ballast Value / Weighting Value (W)

Excess Loss Weighting Factor (w)

Calculate Experience Modifier

function worCalc() { var resultDiv = document.getElementById('wor-result'); resultDiv.style.display = 'none'; resultDiv.innerHTML = '';

// --- Parse inputs --- var AP = parseFloat(document.getElementById('wor-actual-primary').value); var AE = parseFloat(document.getElementById('wor-actual-excess').value); var EP = parseFloat(document.getElementById('wor-expected-primary').value); var EE = parseFloat(document.getElementById('wor-expected-excess').value); var B = parseFloat(document.getElementById('wor-ballast').value); var w = parseFloat(document.getElementById('wor-weight').value);

// --- Validation --- var errors = []; if (isNaN(AP) || AP 1) errors.push("Excess Loss Weighting Factor must be between 0 and 1.");

if (errors.length > 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = 'Please fix the following:' + errors.map(function(e){ return ''; }).join('') + ''; return; }

// --- NCCI Experience Modifier Formula --- // EMR = (Actual Primary Losses + w * Actual Excess Losses + Ballast) // / (Expected Primary Losses + w * Expected Excess Losses + Ballast) // // Numerator = AP + (w * AE) + B // Denominator = EP + (w * EE) + B

var numerator = AP + (w * AE) + B; var denominator = EP + (w * EE) + B;

if (denominator === 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = 'Denominator is zero — check your inputs.'; return; }

var emr = numerator / denominator; emr = Math.round(emr * 1000) / 1000; // round to 3 decimal places (industry standard)

// --- Interpretation ---
var interpretation = '';
var interpClass = '';
if (emr = 1
? 'Premium surcharge: +' + premiumImpact + '%'
'Premium discount: ' + premiumImpact + '%';

// --- Build output --- resultDiv.style.display = 'block'; resultDiv.innerHTML = '### Experience Modifier (X-Mod / EMR) ' + '' + emr.toFixed(3) + '' + '' + interpretation + '

' + '' + premiumLabel + '

' + '' + '#### Calculation Breakdown ' + '' + 'ComponentValue' + 'Actual Primary Losses (AP)$' + AP.toLocaleString('en-US', {minimumFractionDigits:2}) + '' + 'Weighted Actual Excess (w × AE)$' + (w * AE).toLocaleString('en-US', {minimumFractionDigits:2}) + '' + 'Ballast (B)$' + B.toLocaleString('en-US', {minimumFractionDigits:2}) + '' + 'Numerator$' + numerator.toLocaleString('en-US', {minimumFractionDigits:2}) + '' + 'Expected Primary Losses (EP)$' + EP.toLocaleString('en-US', {minimumFractionDigits:2}) + '' + 'Weighted Expected Excess (w × EE)$' + (w * EE).toLocaleString('en-US', {minimumFractionDigits:2}) + '' + 'Ballast (B)$' + B.toLocaleString('en-US', {minimumFractionDigits:2}) + '' + 'Denominator$' + denominator.toLocaleString('en-US', {minimumFractionDigits:2}) + '' + 'Experience Modifier' + emr.toFixed(3) + '' + ''; }

#### Formula

The NCCI (National Council on Compensation Insurance) Experience Modifier formula:

EMR = (AP + w·AE + B) / (EP + w·EE + B)

Where: AP = Actual Primary Losses (losses capped at the split point per claim, typically $5,000) AE = Actual Excess Losses (losses above the split point per claim) EP = Expected Primary Losses (from payroll × class code primary loss rate) EE = Expected Excess Losses (from payroll × class code excess loss rate) w = Excess Loss Weighting Factor (0–1, assigned by rating bureau based on size) B = Ballast Value (stabilizing constant, assigned by rating bureau) EMR = Experience Modifier Rate (rounded to 3 decimal places)

The modifier is applied to the manual premium: Modified Premium = Manual Premium × EMR

#### Assumptions & References

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References

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