Bay Farm Island, Alameda vs Lafayette
Bay Farm Island, Alameda carries an effective property tax rate of 1.22% of assessed value and Lafayette carries 1.07%, both for fiscal year 2025-26. On one identical reference loan the monthly carrying costs are $9,917 and $9,717 — $200 apart, with Lafayette lower. To Oakland City Center at AM peak the fastest published commutes are 20 min by car from Bay Farm Island, Alameda and 22 min by BART from Lafayette. Every figure is an objective public metric or arithmetic on one, and names its source.
Bay Farm Island, Alameda (Alameda County) · Lafayette (Contra Costa County)
| Metric | Bay Farm Island, Alameda | Lafayette | Difference |
|---|---|---|---|
| Median $/sqft (SFR) | $750 | $1,150 | −$400 |
| Effective tax rate | 1.22% | 1.07% | +0.150% |
| Monthly cost, reference loan | $9,917 | $9,717 | +$200 |
| FiDi SF (Montgomery St BART) — BART | 45 min | 40 min | +5 min |
| FiDi SF (Montgomery St BART) — Drive | 40 min | 48 min | −8 min |
| Oakland City Center (12th St BART) — BART | 35 min | 22 min | +13 min |
| Oakland City Center (12th St BART) — Drive | 20 min | 27 min | −7 min |
| Sunnyvale / Mountain View (Sunnyvale Caltrain) — Drive | 55 min | 68 min | −13 min |
Difference is Bay Farm Island, Alameda minus Lafayette. Sources are cited on each submarket page.
Alameda (Bay Farm) is the cheaper foot by $400, 35% below Lafayette. What that buys is a different house, not a different bill: at $1,600,000 the two are $200 apart a month at 1.22% and 1.07%.
Square footage per dollar
Bay Farm comps run $800-$900 per square foot detached and the high $600s for lagoon townhomes. Lafayette comps run $850-$950 per square foot; Happy Valley and the Reliez Valley acre lots begin at $2.5M. Posted medians are $750 per square foot in Alameda (Bay Farm) and $1,150 in Lafayette, a $400 spread.
What the bill looks like
Modelled the same way in both ($1,600,000 purchase, 20% down, 6.5% fixed, $2,400 insurance, dues excluded), Alameda (Bay Farm) totals $9,917 a month at 1.22% and Lafayette $9,717 at 1.07% — tax lines of $1,627 and $1,427. Harbor Bay Isle dues run $150-$200 a month depending on the village. No Mello-Roos in Lafayette, and no HOA on most detached homes; downtown condos run $500-$700 a month.
Getting to work
To Sunnyvale / Mountain View (Sunnyvale Caltrain): 55 minutes by driving from Alameda (Bay Farm), 68 by driving from Lafayette — a 13-minute edge to Alameda (Bay Farm), or 2.2 hours across a ten-trip week. To FiDi SF (Montgomery St BART): 35 minutes by ferry from Alameda (Bay Farm), 40 by BART from Lafayette — a 5-minute edge to Alameda (Bay Farm), or 0.8 hours across a ten-trip week. The Harbor Bay terminal is a five-minute drive or ten-minute bike from most of the island. From Burton Valley the Lafayette station is a 10-minute drive and its lot fills by 7:30 a.m.
What the disclosure stack holds
Most of Bay Farm is engineered fill, so liquefaction is the standing disclosure. Septic on the Reliez and Happy Valley lots adds an inspection line to Lafayette's fire exposure. Verify any parcel against the CAL FIRE Fire Hazard Severity Zone map, the FEMA Flood Map Service Center and the California Geological Survey seismic hazard zones before removing contingencies.
The housing need each answers
Bay Farm answers a townhome-pricing requirement with a flat, short bike commute. Lafayette is the Lamorinda option when one-level living is non-negotiable. The decision is which requirement is load-bearing, because neither submarket satisfies both lists.
Sources. Effective rates and carrying costs: Alameda County Tax Rates by TRA FY 2025-26; Contra Costa TRA Book FY 2025-26, composited in build/assets/metrics.json; TRA-level verification pending, so confirm the rate on the parcel's own bill. Commute times: door-to-door AM-peak estimates, data/commute/static.csv. The per-foot medians are trailing and carry no appraisal weight; the neighborhood detail is first-hand broker observation.
Compare any two submarkets
| Metric | Bay Farm Island, Alameda | Lafayette |
|---|---|---|
| Median $/sqft (SFR) | $750 | $1,150 |
| Effective tax rate | 1.22% | 1.07% |
| Monthly cost, reference loan | $9,917 | $9,717 |
| Fastest to FiDi SF (Montgomery St BART) | 35 min | 40 min |
| Fastest to Oakland City Center (12th St BART) | 20 min | 22 min |
| Fastest to Sunnyvale / Mountain View (Sunnyvale Caltrain) | 55 min | 68 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.
Lafayette detail
| Component | Rate of assessed value |
|---|---|
| Prop 13 general levy | 1.000% |
| County / city voter-approved bonds | 0.012% |
| School district measures | 0.058% |
| Effective rate | 1.07% |
| Mello-Roos / CFD | None recorded |
Source: Contra Costa TRA Book FY 2025-26 (Contra Costa 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 Lafayette: questions and answers
- Which has the lower effective property tax rate, Bay Farm Island, Alameda or Lafayette?
- Lafayette, at 1.07% of assessed value against 1.22% for fiscal year 2025-26 — a gap of 0.150%. 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 Lafayette?
- $200 per month on the identical reference loan: Bay Farm Island, Alameda $9,917, Lafayette $9,717. Lafayette 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 Lafayette?
- Bay Farm Island, Alameda. Bay Farm Island, Alameda is 20 min by car; Lafayette is 22 min by BART. Door-to-door, AM peak. Source: data/commute/static.csv.
- What is the price per square foot difference between Bay Farm Island, Alameda and Lafayette?
- $400 per square foot: Bay Farm Island, Alameda $750, Lafayette $1,150. Single-family medians, trailing twelve months. A median is not a valuation of any specific property.