San Mateo County Property Tax Appeals Analysis - 2023
Comprehensive analysis of 1,651 property tax appeals
Executive Summary
618
Decided Cases (37.4%)
1,033
Not Decided (62.6%)
Key Finding #1: 97.6% of decided cases were resolved through settlement (stipulation),
not formal hearings. Only 6 cases (6 or 1%) went to formal hearing.
Key Finding #2: Among 176 cases that achieved reductions,
the median reduction was $170,400 (9.2%).
Key Finding #3: The largest category is "Closed-Withdrawn" with 692 cases (41.9% of all appeals),
suggesting many property owners abandon their appeals.
Key Finding #4: When property owners requested a reduction, they typically got about 72%
of what they asked for (median requested: -13.1%, median achieved: -9.1%).
Appeal Process Hierarchy
Total Appeals: 1,651
│
├─── DECIDED (618, 37.4%) ← Have final outcome with decided values
│ │
│ ├─── Settlement (Stipulation): 603 (97.6% of decided)
│ ├─── Formal Hearing (Reduced): 5 (0.8% of decided)
│ ├─── Formal Hearing (Upheld): 1 (0.2% of decided)
│ └─── Other Decided: 9 (1.5% of decided)
│
└─── NOT DECIDED (1,033, 62.6%) ← No final outcome values
│
├─── Outstanding (Open/Pending): 290 (28.1% of not decided)
│
└─── Closed without decision: 743 (71.9% of not decided)
├─── Withdrawn: 692
├─── Non-Appearance: 30
└─── Other: 21
⚠️ Data Limitation: This dataset does NOT contain hearing/process dates, so we cannot analyze
how fast appeals are processed or how many are completed per month.
SECTION 1: DECIDED CASES - Complete Analysis (The Facts)
These 618 cases have final decided values, representing concrete outcomes we can analyze.
Key Metrics - All Decided Cases
| Metric |
All Decided |
Settlement |
Formal Hearing |
| Total Decided Cases |
618 |
603 |
6 |
| Total Assessed Value |
$387,046,852 |
$377,178,351 |
$7,222,481 |
| Total Decided Value |
$343,958,920 |
$336,089,594 |
$5,861,326 |
| Total Reduction Amount |
$43,087,932 |
$41,088,757 |
$1,361,155 |
| Overall Reduction Rate |
11.1% |
10.9% |
18.8% |
| Median % Change |
-9.1% |
-9.1% |
-6.5% |
|
|
|
|
| Cases with Reduction |
176 (28.5%) |
173 (28.7%) |
2 |
| Cases with Increase |
1 (0.2%) |
1 |
0 |
| Cases with No Change |
2 (0.3%) |
1 |
1 |
|
|
|
|
| Among Cases with Reductions: |
|
|
|
| Average $ Reduction per Case |
$246,412 |
$239,129 |
N/A |
| Median $ Reduction per Case |
$170,400 |
$170,000 |
N/A |
| Average % Reduction |
12.1% |
11.8% |
N/A |
| Median % Reduction |
9.2% |
9.2% |
N/A |
Comprehensive metrics for decided cases, broken down by resolution method
💡 Insight: Settlement cases and formal hearing cases have similar reduction rates (10.9% vs 18.8%),
but settlements represent the vast majority of outcomes (603 vs 6 cases).
Owner Requests vs. Actual Outcomes
Among the 147 decided cases where owner opinion was filed:
- Median owner request: -13.1% reduction
- Median actual outcome: -9.1% reduction
- Success rate: Owners got approximately 72% of their requested reduction
- Gap: 4.0 percentage points
Component-Level Analysis: Where Did Reductions Come From?
| Component |
Cases |
Total Assessed |
Total Decided |
Total Change |
Change % |
| Land |
591 |
$4,412,262,015 |
$3,833,795,238 |
$-578,466,777 |
-13.1% |
| Improvement |
554 |
$8,222,793,293 |
$7,241,005,829 |
$-981,787,464 |
-11.9% |
| Fixture |
50 |
$51,501,370 |
$53,538,192 |
$2,036,822 |
4.0% |
| Personal Property |
81 |
$179,875,511 |
$167,735,136 |
$-12,140,375 |
-6.7% |
| --- TOTAL --- |
618 |
$387,046,852 |
$343,958,920 |
$-43,087,932 |
-11.1% |
Breakdown of assessment changes by property component, with total summary
💡 Key Insight: Improvements (buildings) saw the largest absolute reduction (-$982M),
followed by land (-$578M). Fixtures actually increased slightly (+$2M).
Property Type Analysis
| Property Type |
Cases |
% of Decided |
Success Rate |
Median % Change |
Avg $ Reduction |
| Residential |
604 |
97.7% |
29.1% |
-9.1% |
$246,412 |
| Commercial |
14 |
2.3% |
0.0% |
nan% |
N/A |
Analysis by property type (classified based on component composition)
🎯 Classification Reliability: HIGH
- Residential (604 cases, 97.7%): 89.4% have BOTH land and improvement (classic residential pattern). 88.4% have NO commercial components whatsoever. These are reliably single-family homes, condos, and townhouses.
- Commercial (14 cases, 2.3%): Clear commercial indicators with fixtures/personal property representing 5-43% of total value. Examples: properties with millions in trade fixtures and business equipment.
Classification Method:
• Residential: Properties with primarily land and/or improvements. May have minor fixtures/personal property (<5% of total value).
• Commercial: Properties where fixtures or personal property represent >5% of total assessed value (trade fixtures, business equipment, machinery).
• Mixed/Other: Properties that don't fit clear residential or commercial patterns.
💡 Key Insight: The 97.7% residential rate is realistic for San Mateo County, which is primarily residential.
Homeowners appeal more frequently than commercial property owners. The classification based on component data
provides a reliable filter for residential-only analysis.
Residential Property Data Quality
| Metric |
Count |
Percentage |
| Total Residential Cases |
604 |
97.7% of decided cases |
| With Both Land AND Improvement |
540 |
89.4% of residential |
| With NO Commercial Components |
534 |
88.4% of residential |
| With Minor Commercial Components (<5%) |
70 |
11.6% of residential |
Breakdown showing the reliability of residential classification
✅ Filtering Recommendation:
For residential-only analysis, use: property_type == 'Residential'
Confidence Level: HIGH - Based on clear component patterns (land + improvement, minimal/no commercial components)
Component Data Availability: Land (95.6%), Improvement (93.0%), Fixtures (8.1%), Personal Property (13.1%)
Example Commercial Properties
The 14 commercial properties show clear commercial indicators with significant fixtures and personal property:
| Example |
Description |
| Property A |
Land: $50K, Improvement: $7.4M, Fixtures: $774K (8.8%), Personal Property: $567K (6.4%) |
| Property B |
Land: $25.3M, Improvement: $58.2M, Fixtures: $6.8M (7.0%), Personal Property: $6.7M (6.9%) |
| Property C |
Land: $1.2M, Improvement: $40K, Fixtures: $683K (26.9%), Personal Property: $577K (22.7%) |
These properties clearly have business equipment, trade fixtures, and machinery characteristic of commercial use
SECTION 2: NOT DECIDED CASES - Outstanding & Closed Without Decision
These 1,033 cases either have no final decision yet (outstanding) or closed without reaching a decision.
A. Outstanding Appeals (290 cases)
Status: Still active, pending decision
Comparison with Historical Outcomes
| Category |
Count |
Median Requested Change |
Median Actual Change |
Expected Outcome (if pattern holds) |
| Outstanding Appeals (with owner opinion) |
238 |
-50.0% |
Not yet decided |
~-9.1% reduction |
| Decided Cases (for comparison) |
147 |
-13.1% |
-9.1% |
Actual outcome |
Outstanding appeals compared to historical decided cases
💡 Prediction: The 238 outstanding appeals with owner opinion filed
are requesting a median -50.0% reduction.
If historical patterns hold, they will likely achieve around -9.1% reduction.
B. Closed Without Decision (743 cases)
- Withdrawn: 692 cases (41.9% of ALL appeals) - Property owners withdrew their appeal
- Non-Appearance: 30 cases (1.8%) - Owner didn't show up for hearing
- Other: 21 cases (Invalid, Duplicate, etc.)
⚠️ Critical Insight: The "Withdrawn" category (692 cases, 41.9%) is the
single largest category in the entire dataset - even larger than all decided cases combined (618 cases).
This suggests a significant portion of property owners abandon their appeals, possibly after:
- Informal discussions with the assessor's office
- Realizing their case is weak
- Cost-benefit analysis showing appeal isn't worth pursuing
- Reaching informal settlement (not formally recorded)
Data Quality & Methodology
Data Parsing
Currency values were parsed from formatted strings (e.g., "$5,000,000").
Cells containing "-" or "$-" were treated as missing (NaN). Parsing success rate: 29.7%.
Derived Metrics
- Gross values: Sum of all property components (land, improvement, fixture, personal property)
- Net values: Gross - Exemption (exemptions reduce taxable value)
- Percentage changes: Use minimum base of $10,000 to avoid extreme ratios from small values
Property Type Classification
Properties are classified based on their component composition:
- Residential: Primarily land and/or improvements. May have minor fixtures or personal property (<5% of total value).
- Commercial: Fixtures or personal property represent >5% of total assessed value. These typically include business equipment, trade fixtures, etc.
- Mixed/Other: Properties that don't fit clear patterns.
Data Availability for Classification:
- Land data: 95.6% of decided cases have land values
- Improvement data: 93.0% have improvement values
- Fixture data: 8.1% have fixture values
- Personal Property data: 13.1% have personal property values
Reliability: HIGH - 89.4% of residential properties have both land and improvement data,
providing a very clear signal. The absence of commercial components is itself a strong indicator of residential use.
Resolution Method
- Settlement (Stipulation): Status contains "Stipulation" or "Stipulated"
- Formal Hearing (Reduced): Status contains "Reduced"
- Formal Hearing (Upheld): Status contains "Upheld"
Limitations
- No date fields available - cannot analyze processing speed or completion rates over time
- No assessor recommendation field - cannot compare assessor position to owner request
- Outstanding appeals have limited data (early stages)
- Some closed cases may represent informal settlements not recorded as stipulations
Data Completeness
Total Records: 1,651
With Decided Values: 618 (37.4%)
With Owner Opinion: 1,630 (98.7%)
San Mateo County Property Tax Appeals Analysis
Report Generated: 2024 | Analysis Period: 2023 Appeals