San Mateo County property record for 421 Alder Ln, San Mateo, CA 94403
| Property Type | Single Family Home |
|---|---|
| Details | 3 bd · 2 ba · 1,960 sqft · built 1951 |
| Lot Size | 0.149 acres (6,500 sqft) |
| Owner | 2 Trust Names on File |
| Last Sale | $2,300,000 (Sep 2022) |
| Tax Bill | $28,577 (2025) |
| Deeds & Mortgages | Sep 2022 Sale Sep 2019 Transfer |
| Flood Zone | Zone X (minimal risk) |
| APN | 039-440-760 |
| Primary APN | 039-440-760 |
|---|
| Bedrooms | 3 Beds |
|---|---|
| Full Baths | 2 Baths |
| Total Rooms | 7 Rooms |
| Stories | 1 Story |
| Building Area | 1,960 sqft Living Area |
| 1st Floor Area | 1,480 sqft |
| Family Room | Family Room |
| Fireplaces | 1 Fireplace |
| Fireplace | Fireplace |
| Year Built | Built 1951 |
|---|---|
| Effective Year Built | Effective 1951 |
| Lot Area | 6,500 sqft (0.149 acres) |
| Lot Dimensions | 100 ft deep x 65 ft wide |
| Garage Area | 470 sqft |
| Parking Spaces | 2 Parking Spaces |
| Cooling System | Central |
|---|---|
| Heating System | Central |
| Street Address | 421 ALDER LN |
|---|---|
| City | SAN MATEO |
| State | CA |
| Zip | 94403-3302 |
| Property Category | Residential |
| Property Type | Residential > Single Family > Home |
| Local Zoning Code | R10006 |
| Legal Description | LOT 11 BLOCK 2 HILLSDALE UNIT NO 3 RSM 25/32 33 CITY OF SAN MATEO |
| Legal Subdivision | HILLSDALE UNIT NO 3 |
| Legal Tract | 1 |
| Legal Block | 2 |
| Legal Lot Number | 11 |
| Jurisdiction | SAN MATEO CA |
| Township / Civil Division | SAN MATEO |
| Census Block Group | 2 |
| Census Block | 2014 |
| Census Tract | 607300 |
421 Alder Ln is held in a trust since September 2022.
Source: San Mateo County records, as of July 15, 2026
| Owner of Record | 2 Trust Names on File |
|---|---|
| Mailing Address | 492 PARROTT DR, SAN MATEO, CA 94402-2232 |
| Owner Type | Company |
| Vesting | Trust |
Owner names and exact recorded amounts are on file and can be viewed instantly on this page with a free 10-day trial.
| Date | Document |
|---|---|
| Sep 20, 2022 | Grant Deed, Transfer DOMA TITLE OF CALIFORNIA INC |
| Sep 18, 2019 | Affidavit of Death, Transfer ATTORNEY ONLY |
| Deed Names | 2 Names on Deed |
|---|---|
| Last Sale | Sep 20, 2022 · Amount on File |
| Deed Sale | Sep 20, 2022 · Amount on File |
| Deed Document Number | 202268269 |
| Record Updated | Sep 20, 2026 |
| Document Type | Grant Deed |
|---|---|
| Jurisdiction | SAN MATEO CA |
| Recording Date | Sep 20, 2022 |
| Property Address | 421 ALDER LN, SAN MATEO, CA 94403-3302 |
| Document Number | 0000068269 |
| Map Reference | MB 25 PG 32 |
| Instrument Date | Sep 7, 2022 |
| Instrument | 2022-068269 |
| Transaction Type | Transfer |
| Record Updated | Jun 7, 2023 |
| Title Company | DOMA TITLE OF CALIFORNIA INC |
| Amount | Amount on Record |
|---|---|
| Tax | $14,030.00 |
| Amount Accuracy | Rounded by County |
| Additional |
|
| Name | Verified Name |
|---|
| Name | Verified Name |
|---|---|
| Address | 492 PARROTT DR, SAN MATEO, CA 94402-2232 |
| Document Type | Affidavit of Death |
|---|---|
| Jurisdiction | SAN MATEO CA |
| Recording Date | Sep 18, 2019 |
| Property Address | 421 ALDER LN, SAN MATEO, CA 94403-3302 |
| Document Number | 0000076089 |
| Instrument Date | Aug 30, 2019 |
| Instrument | 76089 |
| Transaction Type | Transfer |
| Record Updated | Oct 4, 2019 |
| Title Company | ATTORNEY ONLY |
| Name | Verified Name |
|---|
| Name | Verified Name |
|---|---|
| Relationship | Personal Trust |
| Address | 421 ALDER LN SAN MATEO CA 944033302, SAN MATEO, CA 94403-3302 |
The 2025 property tax bill for 421 Alder Ln was $28,577.
Source: San Mateo County assessment roll, as of July 15, 2026
| Type | Name |
|---|---|
| State | California |
| County | San Mateo County |
| Municipality | San Mateo City |
| Elementary School District | San Mateo-Foster City Elementary School District (KG - 08) |
| Secondary School District | San Mateo Union High School District (09 - 12) |
| Year | Tax Bill | Assessed Value | Assessed Market Value |
|---|---|---|---|
| 2026 | $2,440,777 (+2%) Land $1,841,195 Building $599,582 | ||
| 2025 | $28,577.00 | $2,392,920 Land $1,805,094 Building $587,826 | |
| 2023 | $27,525.00 (+842.64%) | $2,300,000 Land $1,735,000 Building $565,000 | $1,988,730 |
| 2022 | $2,920.00 |
Assessed value and assessed market value are set for property tax purposes and are not market price estimates.
FEMA maps place 421 Alder Ln in Zone X, an area of minimal flood risk, though there have been 4 flood claims nearby since 1998.
Source: FEMA National Flood Hazard Layer, effective September 10, 2026 · OpenFEMA NFIP redacted claims and policies, as of September 2026
| FEMA Flood Zone | Zone X minimal risk |
|---|---|
| Flood Insurance Requirement | Not required lenders may require it |
| Nearby Flood Policies | 2 in force |
| Nearby Flood Claims | 4 (1998–2022) |
| Claims Outside the SFHA | 4 of 4 |
| Most Recent Claim | Dec 2022 · rainfall accumulation |
Values are read at the parcel center point; flood claims are located to the census block group, not this parcel; lenders make the official flood determination.
The area around 421 Alder Ln has no burnable land within ember reach, so its wildfire risk is not rated.
Source: USDA Forest Service Wildfire Risk to Communities (2nd edition), as of 2024
| Wildfire Risk | Not rated no burnable land within ember reach |
|---|
Values cover an area roughly 900 ft across, not the parcel itself; insurers use their own ratings.
Source: EPA Safe Drinking Water Information System, as of September 2026
| Water System | CALIFORNIA WATER SERVICE - SAN MATEO private · serves 103,536 people · EPA ID CA4110008 |
|---|---|
| Water Source | Purchased surface water from SAN FRANCISCO REGIONAL WATER SYSTEM |
| Last State Inspection | Mar 2025 |
| Lead | 4 ppb (2023–2025) action level 15 ppb |
| Water Quality | None last 10 years |
|---|---|
| Treatment and Procedure | None last 10 years |
| Monitoring and Reporting | None last 3 years |
Results are for the whole water system, not water tested at this address; lead at the tap also depends on the building's own pipes.
Source: FCC Broadband Data Collection, based on 716 locations within half a mile, as of December 31, 2025
| Provider | Max Down / Up (Mbps) |
|---|---|
| Sonic Telecom Fiber | 10,000 / 10,000 |
| AT&T Fiber · Fixed Wireless, DSL in parts of the area | 5,000 / 5,000 |
| Xfinity Cable | 2,000 / 250 |
| Astound Broadband Cable · Fiber in parts of the area | 1,500 / 50 |
May also be available: Etheric Networks, GeoLinks, T-Mobile.
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