Moore Marsden Calculation

Moore-Marsden Property Division Calculator

Calculation Results

Total Property Appreciation:

Separate Property Share Percentage:

Community Property Share Percentage:

Separate Property Interest:

Community Property Interest:

Total Net Equity:

function calculateMooreMarsden() { var purchasePrice = parseFloat(document.getElementById('purchasePrice').value) || 0; var currentValue = parseFloat(document.getElementById('currentValue').value) || 0; var downPayment = parseFloat(document.getElementById('downPayment').value) || 0; var preMaritalPaydown = parseFloat(document.getElementById('preMaritalPaydown').value) || 0; var maritalPaydown = parseFloat(document.getElementById('maritalPaydown').value) || 0; var mortgageBalance = parseFloat(document.getElementById('mortgageBalance').value) || 0; if (purchasePrice <= 0 || currentValue <= 0) { alert("Please enter valid purchase and current market values."); return; } var totalAppreciation = currentValue – purchasePrice; var totalEquity = currentValue – mortgageBalance; // The community percentage is based on the principal reduction during marriage relative to purchase price var cpPercentage = maritalPaydown / purchasePrice; // The separate property percentage is the remainder of the purchase price basis var spPercentage = (purchasePrice – maritalPaydown) / purchasePrice; // CP Interest = Principal reduction during marriage + (CP Percentage * Appreciation) var cpInterest = maritalPaydown + (cpPercentage * totalAppreciation); // SP Interest = Down Payment + Pre-marital reduction + (SP Percentage * Appreciation) var spInterest = downPayment + preMaritalPaydown + (spPercentage * totalAppreciation); document.getElementById('resAppreciation').innerText = '$' + totalAppreciation.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resSPPercent').innerText = (spPercentage * 100).toFixed(2) + '%'; document.getElementById('resCPPercent').innerText = (cpPercentage * 100).toFixed(2) + '%'; document.getElementById('resSPInterest').innerText = '$' + spInterest.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resCPInterest').innerText = '$' + cpInterest.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('resTotalEquity').innerText = '$' + totalEquity.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('mmResult').style.display = 'block'; }

Understanding the Moore-Marsden Calculation

The Moore-Marsden calculation is a legal formula used primarily in California family law to determine the division of real estate equity when a spouse brings a property into a marriage as separate property, but community property funds are used to pay down the mortgage during the marriage.

How the Formula Works

The core philosophy of Moore-Marsden is that both the separate property owner and the community (the marriage) should benefit from the appreciation of the property in proportion to their respective contributions to the purchase price.

• Separate Property Contribution: Includes the original down payment and any principal paydown made before the marriage began.
• Community Property Contribution: Consists specifically of the reduction in mortgage principal made with community funds (usually income earned during the marriage).
• Capital Appreciation: The increase in property value from the date of purchase to the date of trial/valuation.

The Step-by-Step Logic

1. Determine the Percentages: The community interest is calculated by dividing the marital principal reduction by the original purchase price. The separate interest owns the remainder of the original purchase price basis.
2. Divide Appreciation: The total appreciation is multiplied by these percentages to allocate how much "growth" belongs to each party.
3. Aggregate Interest: The community interest is the sum of its principal paydown plus its share of appreciation. The separate interest is the sum of the down payment, pre-marital paydown, and its share of appreciation.

Practical Example

Imagine a home purchased for $500,000 before marriage. One spouse paid $50,000 down. Before getting married, they paid off $25,000 of the principal. During 10 years of marriage, $75,000 in principal was paid using marital income. The house is now worth $900,000.

• Total Appreciation: $400,000 ($900k – $500k)
• Community Ratio: $75,000 / $500,000 = 15%
• Separate Ratio: ($500,000 – $75,000) / $500,000 = 85%
• Community Share: $75,000 (paydown) + $60,000 (15% of appreciation) = $135,000
• Separate Share: $75,000 (down+pre-paydown) + $340,000 (85% of appreciation) = $415,000

Important Considerations

Note that Moore-Marsden typically deals only with principal paydown. Property taxes, mortgage interest, and insurance premiums paid with community funds are generally not included in this calculation, as they do not contribute to the equity in the home. Additionally, if improvements were made to the property using community funds, a different calculation (often called a Moore-Marsden-Branco analysis) may be required to account for the added value.

Disclaimer: This calculator is for educational purposes only. Divorce law and property division can be complex. You should consult with a qualified family law attorney or forensic accountant in your jurisdiction for legal advice.