Bay Farm Island, Alameda vs Foster City
Bay Farm Island, Alameda carries an effective property tax rate of 1.22% of assessed value and Foster City carries 1.10%, both for fiscal year 2025-26. On one identical reference loan the monthly carrying costs are $9,917 and $9,760 — $157 apart, with Foster City lower. To Oakland City Center at AM peak the fastest published commutes are 20 min by car from Bay Farm Island, Alameda and 40 min by car from Foster City. Every figure is an objective public metric or arithmetic on one, and names its source.
Bay Farm Island, Alameda (Alameda County) · Foster City (San Mateo County)
| Metric | Bay Farm Island, Alameda | Foster City | Difference |
|---|---|---|---|
| Median $/sqft (SFR) | $750 | $1,000 | −$250 |
| Effective tax rate | 1.22% | 1.10% | +0.118% |
| Monthly cost, reference loan | $9,917 | $9,760 | +$157 |
| FiDi SF (Montgomery St BART) — BART | 45 min | 58 min | −13 min |
| FiDi SF (Montgomery St BART) — Drive | 40 min | 45 min | −5 min |
| Oakland City Center (12th St BART) — BART | 35 min | 70 min | −35 min |
| Oakland City Center (12th St BART) — Drive | 20 min | 40 min | −20 min |
| Sunnyvale / Mountain View (Sunnyvale Caltrain) — Drive | 55 min | 30 min | +25 min |
Difference is Bay Farm Island, Alameda minus Foster City. Sources are cited on each submarket page.
Put the two side by side and the gap is square footage, not tax: $750 per foot in Alameda (Bay Farm) against $1,000 in Foster City. On the same $1,600,000 purchase the monthly separation is $157, because Alameda (Bay Farm) bills 1.22% and Foster City 1.10%.
The house at each price
$1.4M on Bay Farm Island is a 1980s-90s detached home of 1,700-2,000 sq ft with a small lot and two-car garage. Foster City comps run $950-$1,100 per square foot detached and $800-$900 for townhomes. The median foot costs $750 in Alameda (Bay Farm) against $1,000 in Foster City; on a 2,000 sq ft house that is $500,000 of purchase price.
What the bill looks like
Holding the loan constant — $1,600,000, 20% down, 6.5% on a 30-year fixed, $2,400 of insurance, no HOA — Alameda (Bay Farm) totals $9,917 a month at 1.22% and Foster City $9,760 at 1.10% — tax lines of $1,627 and $1,469. Harbor Bay Isle dues run $150-$200 a month depending on the village. Foster City's 2018 levee improvement assessment shows as its own line at $200-$400.
Commute, measured
To Sunnyvale / Mountain View (Sunnyvale Caltrain): 55 minutes by driving from Alameda (Bay Farm), 30 by driving from Foster City — a 25-minute edge to Foster City, or 4.2 hours across a ten-trip week. To Oakland City Center (12th St BART): 20 minutes by driving from Alameda (Bay Farm), 40 by driving from Foster City — a 20-minute edge to Alameda (Bay Farm), or 3.3 hours across a ten-trip week. Bay Farm has no BART; Coliseum station is a 12-minute drive. Driving 101 from Foster City to SoMa is 25 minutes at 6 a.m. and 45-60 at 8.
Hazard and insurance
Bay Farm Island is not wildland-urban interface. Lenders still sometimes ask for Foster City flood coverage; $500-$1,200 a year is the conservative quote. Run the address through CAL FIRE's severity-zone viewer, the FEMA Flood Map Service Center and the CGS seismic hazard maps, and treat the premium quote as a contingency item.
The housing need each answers
Bay Farm is the option when the water crossing is the commute. Foster City is the answer when lagoon townhome living beats a fixer.
Sources. Tax figures come from Alameda County Tax Rates by TRA FY 2025-26; San Mateo County Tax Rate Book FY 2025-26, composited in build/assets/metrics.json. They are county-level and not yet verified at the TRA, so the parcel's bill governs. Travel times are AM-peak door-to-door estimates from data/commute/static.csv. Median price per foot is a trailing figure, not a valuation, and the local detail comes from the broker's own transactions.
Compare any two submarkets
| Metric | Bay Farm Island, Alameda | Foster City |
|---|---|---|
| Median $/sqft (SFR) | $750 | $1,000 |
| Effective tax rate | 1.22% | 1.10% |
| Monthly cost, reference loan | $9,917 | $9,760 |
| Fastest to FiDi SF (Montgomery St BART) | 35 min | 45 min |
| Fastest to Oakland City Center (12th St BART) | 20 min | 40 min |
| Fastest to Sunnyvale / Mountain View (Sunnyvale Caltrain) | 55 min | 30 min |
Same reference loan on both sides; the tax line is the only variable. Commute figures are door-to-door AM-peak estimates. Sources are listed on each submarket page.
Bay Farm Island, Alameda detail
| Component | Rate of assessed value |
|---|---|
| Prop 13 general levy | 1.000% |
| County / city voter-approved bonds | 0.042% |
| School district measures | 0.178% |
| Effective rate | 1.22% |
| Mello-Roos / CFD | None recorded |
Source: Alameda County Tax Rates by TRA FY 2025-26 (Alameda County), composited in
build/assets/metrics.json.
Tax Rate Area not yet verified parcel-by-parcel — confirm the rate on the parcel’s own tax bill.
Foster City detail
| Component | Rate of assessed value |
|---|---|
| Prop 13 general levy | 1.000% |
| County / city voter-approved bonds | 0.010% |
| School district measures | 0.092% |
| Effective rate | 1.10% |
| Mello-Roos / CFD | None recorded |
Source: San Mateo County Tax Rate Book FY 2025-26 (San Mateo County), composited in
build/assets/metrics.json.
Tax Rate Area not yet verified parcel-by-parcel — confirm the rate on the parcel’s own tax bill.
Bay Farm Island, Alameda vs Foster City: questions and answers
- Which has the lower effective property tax rate, Bay Farm Island, Alameda or Foster City?
- Foster City, at 1.10% of assessed value against 1.22% for fiscal year 2025-26 — a gap of 0.120%. Rates are composited from county tax rate books; each parcel bill governs.
- How much do monthly carrying costs differ between Bay Farm Island, Alameda and Foster City?
- $157 per month on the identical reference loan: Bay Farm Island, Alameda $9,917, Foster City $9,760. Foster City is lower. Principal and interest are held constant, so the difference is the tax line. Arithmetic only.
- Which has the shorter commute to Oakland City Center, Bay Farm Island, Alameda or Foster City?
- Bay Farm Island, Alameda. Bay Farm Island, Alameda is 20 min by car; Foster City is 40 min by car. Door-to-door, AM peak. Source: data/commute/static.csv.
- What is the price per square foot difference between Bay Farm Island, Alameda and Foster City?
- $250 per square foot: Bay Farm Island, Alameda $750, Foster City $1,000. Single-family medians, trailing twelve months. A median is not a valuation of any specific property.