What Is Moore-Marsden Apportionment?
When community funds pay down the mortgage on a house one spouse owned before the marriage, who gets the benefit of the house’s rising value? California answers this with Moore-Marsden apportionment: the community earns a pro rata share of the property’s appreciation, calculated from the fraction of the loan principal paid off with community funds — not just a dollar-for-dollar reimbursement of what was paid.
This formula is, by most accounts, the single most heavily tested calculation on the California Bar Exam’s community property essays. If you can run the math cold, you can pick up significant points even under time pressure.
The Rule: A Pro Rata Share, Not Simple Reimbursement
Moore-Marsden apportionment, defined: when a spouse’s premarital separate property is purchased with a loan, and community funds are later used during marriage to pay down the loan’s principal, the community is entitled to a pro rata share of the property’s appreciation — calculated as the ratio of community principal payments to the original purchase price — plus the principal itself, rather than a flat reimbursement of the dollars paid.
This comes from two cases: In re Marriage of Moore (1980), which established the pro rata appreciation share, and In re Marriage of Marsden (1982), which refined the rule for properties purchased well before the marriage.
The Formula
| Component | Formula |
|---|---|
| CP’s principal fraction | Community principal paid ÷ Original purchase price |
| CP’s share of appreciation | CP’s principal fraction × Total appreciation |
| CP’s total share | CP’s share of appreciation + Community principal paid |
| SP’s total share | Total current value − CP’s total share |
Critical limitation: only principal reduction counts. Interest, property taxes, insurance, and maintenance are carrying costs — they do not build equity and are excluded from the formula entirely.
Worked Example 1: Basic Application
Facts: Before marrying, a single homeowner buys a house for $100,000, using a $20,000 separate property down payment and an $80,000 loan. After marriage, the couple pays off the entire $80,000 loan using community funds. By the time of divorce, the house is worth $250,000.
Calculation:
- Appreciation = $250,000 − $100,000 = $150,000
- CP’s principal fraction = $80,000 ÷ $100,000 = 0.8
- CP’s share of appreciation = 0.8 × $150,000 = $120,000
- CP’s total share = $120,000 + $80,000 = $200,000
- SP’s total share = $250,000 − $200,000 = $50,000
Notice that the community ends up with the vast majority of the house’s value — not because it paid all $80,000 in principal, but because that principal payment, run through the formula, also captures 80% of the appreciation.
The Marsden Refinement: When the Marriage Comes Later
Marsden addresses a common wrinkle: what if the spouse bought the property well before the marriage, and it had already appreciated by the wedding date? The rule carves out pre-marital appreciation as pure separate property, and only apportions appreciation that accrued during the marriage.
- The CP’s principal fraction still uses the original purchase price as the denominator — that part of the Moore formula doesn’t change.
- But the appreciation figure itself changes: instead of (value at division − purchase price), you use (value at division − value at the date of marriage).
Worked Example 2: Applying the Marsden Refinement
Facts: In 2005, a spouse buys a rental property for $200,000 ($50,000 separate property down payment, $150,000 purchase-money mortgage). She marries in 2010; by then, the property is already worth $260,000 — that $60,000 of pre-marital gain is hers alone as separate property. During the marriage (2010-2020), the couple pays the $150,000 loan down to zero using community funds. At divorce in 2020, the property is worth $400,000.
Calculation:
- CP’s principal fraction (against original purchase price) = $150,000 ÷ $200,000 = 0.75
- Appreciation subject to apportionment = $400,000 − $260,000 (value at marriage) = $140,000
- CP’s share of that appreciation = 0.75 × $140,000 = $105,000
- CP’s total share = $105,000 + $150,000 = $255,000
- SP’s total share = $400,000 − $255,000 = $145,000 (the $50,000 down payment, plus $60,000 pre-marital appreciation, plus $35,000 as SP’s 25% share of marital appreciation)
Worked Example 3: Why Interest and Taxes Don’t Count
Facts: A $100,000 house, purchased with an $80,000 separate property loan. Over ten years of marriage, the community pays $30,000 toward principal, $40,000 toward interest, and $15,000 toward taxes and insurance. The house appreciates to $180,000.
Calculation:
- Only the $30,000 principal payment counts — the $40,000 interest and $15,000 taxes/insurance are excluded entirely.
- CP’s principal fraction = $30,000 ÷ $100,000 = 0.30
- Appreciation = $180,000 − $100,000 = $80,000
- CP’s share of appreciation = 0.30 × $80,000 = $24,000
- CP’s total share = $24,000 + $30,000 = $54,000
Students who mistakenly include the $40,000 interest payment in the numerator will badly overstate the community’s share — this is the exam’s single most common Moore-Marsden trap.
The Two Classic Fact Patterns
Moore-Marsden shows up in essentially two recurring scenarios:
- An installment purchase begun before marriage, whose loan is paid down with community funds after marriage.
- An inherited or gift-received separate property carrying a mortgage that gets paid down with community funds during marriage.
In both, no gift to the community is ever presumed — even if the non-owner spouse personally makes the mortgage payments or otherwise approves the arrangement. The community earns its pro rata share as a matter of law, not by agreement.
Common Mistakes to Avoid
- Confusing Moore-Marsden with simple reimbursement. The community isn’t just getting its money back — it’s getting a proportional share of appreciation, which is often far larger than the raw dollars paid.
- Including interest, taxes, or insurance in the numerator. Only principal reduction counts toward the community’s fraction.
- Using the value at the date of marriage as the denominator. The denominator is always the original purchase price, even under the Marsden refinement — only the appreciation figure changes to account for the marriage date.
- Confusing this doctrine with the feathering-the-nest reimbursement rule. If a loan taken out during marriage funds renovations to a spouse’s own separate property and is repaid with community funds, that’s a different doctrine entirely — the community’s remedy there is the greater-of-cost-or-value-added reimbursement, not Moore-Marsden apportionment.
Why This Matters for the California Bar Exam
Moore-Marsden essays are formula-driven, and graders reward showing your work. Identify the purchase price, the community principal payments, the property’s value at the relevant dates, and whether a Marsden pre-marital appreciation carve-out applies. Run the fraction, apply it to the correct appreciation figure, and add back the principal paid. Precision matters more than speed here.
FAQ
Does Moore-Marsden apply to interest payments made with community funds?
No. Only principal reduction counts toward the community’s share. Interest, taxes, insurance, and maintenance are carrying costs excluded from the formula.
What’s the difference between the Moore rule and the Marsden refinement?
Moore establishes that the community gets a pro rata share of appreciation based on principal payments. Marsden refines this for properties purchased well before the marriage, carving out pre-marital appreciation as separate property and apportioning only appreciation accrued during the marriage.
Is Moore-Marsden the same as the feathering-the-nest reimbursement rule?
No. Moore-Marsden applies when community funds pay down a loan used to purchase separate property. If community funds instead pay for a loan that funds improvements to a spouse’s own separate property, the feathering-the-nest greater-of-cost-or-value-added rule applies instead.
Key Takeaways
- Moore-Marsden gives the community a pro rata share of appreciation on separate property, based on the fraction of the original purchase price paid off with community principal.
- The formula is: (community principal ÷ original purchase price) × appreciation + community principal paid.
- Only principal counts — never interest, taxes, insurance, or maintenance.
- The Marsden refinement carves out pre-marital appreciation as separate property when the purchase predates the marriage, but still uses the original purchase price as the fraction’s denominator.
- No gift to the community is ever presumed, even if the non-owner spouse makes or approves the mortgage payments.
This article is educational and is not legal advice. Consult a licensed California attorney about your situation.
Related guides
- community property presumptions
- feathering the nest doctrine
- community credit presumption
- spousal fiduciary duty