Moore/Marsden Calculator — California Real Estate Apportionment
Free online Moore/Marsden calculator for California divorce cases. When one spouse owned real property before marriage and community funds paid down the mortgage principal during marriage, In re Marriage of Moore (1980) and In re Marriage of Marsden (1982) entitle the community to a pro tanto interest equal to CP principal ÷ purchase price, plus that same share of any appreciation that occurred during the marriage. Pre-marital appreciation stays with the SP owner. This tool computes the full split — SP reimbursement, CP pool, and each spouse's takeaway — for retained or sold properties.
The tool derives CP principal paid during marriage from the drop in loan balance between marriage and division. Pull those two balances from your loan statements — that's the cleanest way to capture what the community actually paid down, automatically excluding interest, taxes, insurance, and HOA. No statements on hand? The amortization helper on each property builds a full schedule from the loan's APR + term.
This is a calculation tool, not legal advice. Results are based on the inputs you provide and general Moore/Marsden methodology; they don't substitute for case-specific analysis by a family-law attorney or CPA.
⚠️ Not supported:
SP → CP conversion during marriage (e.g., adding the other spouse to title or refinancing into a joint loan). Consult counsel.
Homes sold before DOS — a CPA tracing is needed to verify whether the proceeds were reinvested and kept their SP character or became CP through commingling.
Timeline
Date
Value
Loan balance
Purchase
At Marriage
2021-06-15
from Case Details
At Division
2024-02-29
DOS · from Case Details
For records — doesn't change pro tanto math.
Capital Improvements
Log significant improvements (kitchen remodel, new roof, addition, etc.) with date, cost, and funding source. Repairs and routine maintenance don't count — only capital items that add to cost basis.
CP paydown is the numerator of the pro tanto ratio. SP paydown is shown for completeness — it's already baked into the SP equity at marriage, so it doesn't directly enter the pro tanto math. Only balance drops count; interest, taxes, insurance, and HOA don't build equity. If SP funds were used to pay principal during marriage, subtract that from the CP paydown figure manually (there's room in the notes to document it).
Notes
Moore/Marsden result — Primary Residence
SP principal paid pre-marriage:$90,000.00
CP principal paid during marriage:$80,000.00
Pro tanto (CP principal ÷ purchase price):9.41%
Appreciation during marriage:$150,000.00
CP share of that appreciation:$14,117.65
CP total interest (principal reimbursement + share of appreciation):$94,117.65
Total equity at division (FMV − mortgage):$740,000.00
SP total interest (remaining equity):$645,882.35
Each spouse's takeaway
Employee (SP owner):$692,941.18
Spouse:$47,058.82
Timeline
Date
Value
Loan balance
Purchase
At Marriage
2021-06-15
from Case Details
At Division
2024-02-29
DOS · from Case Details
For records — doesn't change pro tanto math.
Capital Improvements
Log significant improvements (kitchen remodel, new roof, addition, etc.) with date, cost, and funding source. Repairs and routine maintenance don't count — only capital items that add to cost basis.
CP paydown is the numerator of the pro tanto ratio. SP paydown is shown for completeness — it's already baked into the SP equity at marriage, so it doesn't directly enter the pro tanto math. Only balance drops count; interest, taxes, insurance, and HOA don't build equity. If SP funds were used to pay principal during marriage, subtract that from the CP paydown figure manually (there's room in the notes to document it).
Notes
Moore/Marsden result — Downtown Condo
SP principal paid pre-marriage:$24,000.00
CP principal paid during marriage:$52,000.00
Pro tanto (CP principal ÷ purchase price):10.00%
Appreciation during marriage:$120,000.00
CP share of that appreciation:$12,000.00
CP total interest (principal reimbursement + share of appreciation):$64,000.00
Total equity at division (FMV − mortgage):$380,000.00
SP total interest (remaining equity):$316,000.00
Each spouse's takeaway
Employee:$32,000.00
Spouse (SP owner):$348,000.00
Portfolio summary
Total equity across all properties:$1,120,000.00
SP reimbursements (first claim)
To Employee:$645,882.35
To Spouse:$316,000.00
Total reimbursed:$961,882.35
Community property to divide
CP remaining after reimbursements:$158,117.65
Each party's half:$79,058.82
Each party's total takeaway
Employee (SP reimbursement + CP half):$724,941.18
Spouse (SP reimbursement + CP half):$395,058.82
Moore/Marsden (CA)
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