Sonoma County Property Tax
The average property-tax rate in Sonoma County is about 1.14% of assessed value (Board of Equalization county average, 2024-25) — the 1% Proposition 13 base levy plus each area's voter-approved debt. That's above the statewide average of about 1.11%, making it the 15th-highest of California's 58 counties (the 44th-lowest). On a $500,000 assessed value that's roughly $5,695 a year. Estimate your own bill below, or jump to due dates & where to pay or Sonoma property tax by city (rates and typical bills) and assessed value by city.
Sonoma County property tax: the short answers
- Due dates (2026–27). First installment due Sunday, November 1, 2026, pay by 5 p.m. Thursday, December 10, 2026; second due Monday, February 1, 2027, pay by 5 p.m. Monday, April 12, 2027 (April 10 is a Saturday). Sonoma County has not published a 2026–27 mailing date; bills must go out by November 1 (§2610.5).
- Where to pay. Online at sonomacounty.gov/acttc/pay-your-property-tax-bill-online (search by parcel number or address); fees as the county lists them: e-check free, card 2.34%.
- Typical bill. The county's average single-family home is assessed at about $607,376 (Board of Equalization, 2025), which at the 1.139% county average comes to about $6,918 a year before Mello-Roos and direct charges. A new buyer pays on the purchase price instead.
- Your rate depends on where you are. Across Sonoma County's 728 Tax Rate Areas the ad-valorem rate runs from 1.06% to 1.17% (2026/2027 rate book); see what is in your rate.
- By city. Sonoma property tax by city: each city's typical rate and bill.
- Look up a parcel. Sonoma County Assessor for assessed value and exemptions; the tax collector's portal above for the bill itself.
How Sonoma County property tax is calculated
California taxes property under Proposition 13: your assessed value is generally set when you buy, then rises no more than 2% a year until the property changes hands or is newly built. The annual bill is that assessed value times the ad-valorem rate — the 1% base plus voter-approved bonds — which is why Sonoma County's average works out to about 1.14%. Because the bonds differ by Tax Rate Area, two homes in the same county can pay slightly different rates.
What changed in Sonoma County's rates for 2026-27
Comparing the county's 2026-27 rate book with 2025-26, Tax Rate Area by Tax Rate Area, the parcel-weighted median ad-valorem rate fell from 1.1347% to 1.1295% (−0.0052 points). Rates went up for 3.7% of the county's 187,449 parcels in rated areas and down for 96.3%. The 1% Proposition 13 base never moves; what moved is the voter-approved debt on top of it, which each agency recalculates every year from the bonds it must repay and the assessed value that repays them.
- SOCO JR COLLEGE 2002 BOND: 0.0110% → 0.0090% (−0.0020), on about 188,099 parcels — community college district bonds.
- SR HIGH DIST 2002 BOND: 0.0070% → 0.0035% (−0.0035), on about 70,191 parcels — school district facilities bonds.
- SR HIGH DIST 2014 BOND: 0.0170% → 0.0150% (−0.0020), on about 70,191 parcels — school district facilities bonds.
Every Tax Rate Area's move, the levies behind it and the other counties with a 2026-27 book are on California property tax rate changes for 2026-27 →
What's on a property tax bill
Ad-valorem tax (1% base + voter-approved debt) · Mello-Roos special taxes, where a parcel is in a Community Facilities District (how long they last) · fixed direct assessments (lighting, sewer, etc.). Only the first is value-based; the 1.14% rate covers that part.
Learn the rules behind the rate: how California property tax is calculated, Proposition 13, Mello-Roos, and what triggers a reassessment.
Want your exact rate, not the county average? See what's in your Sonoma County property tax → — browse by city and Tax Rate Area, or look up your parcel, for the itemized ad-valorem breakdown.
Some Sonoma County communities also pay a Mello-Roos special tax — see the Sonoma County CFD district list → with each district's bond debt and delinquency.
Sonoma County property tax by the numbers
How much is property tax in Sonoma County? For an existing owner the average single-family home is assessed near $607,376, so at the county's 1.139% average rate (Board of Equalization county average, 2024-25) the implied bill is about $6,918 a year (a mean across all existing owners, not a median). A new buyer is taxed on the purchase price instead — use the calculator above. The figures below are the county-level activity behind that rate.
Sources: California State Board of Equalization (assessors' workload tables, Table E1 single-family values, property-tax allocation), the California Debt and Investment Advisory Commission (Mello-Roos roster), the California FAIR Plan Association (policies in force by county) and CAL FIRE / OSFM fire hazard severity zones weighted by 2020 housing units. County aggregates only, no parcel or owner identities; counts are filings processed and can lag the event year. Verify with the Sonoma County Assessor before relying on them.
Due dates & where to pay
Sonoma County property taxes are paid in two installments: first due November 1 (delinquent after December 10) and second due February 1 (delinquent after April 10). A 10% penalty applies after each delinquency date, and a bill still unpaid on July 1 becomes tax-defaulted; after five years in default the county may sell it at auction (see the California tax sale calendar). Boats, aircraft and business equipment are billed separately on the unsecured roll, due in one payment by August 31. Pay or look up a parcel through the Sonoma County Treasurer-Tax Collector. Portal links, fees and missing-bill numbers for every county are on one look-up-and-pay page.
These deadlines are set by California state law (Revenue & Taxation Code §§ 2605, 2606, 2617 and 2701) and are the same in every county — this is general education, not a county-by-county check. If a delinquency date falls on a weekend or legal holiday, it moves to the next business day. Always confirm the exact dates and amounts on your own tax bill and your county tax collector's website. See the full California property tax due-date calendar for the dated 2026–27 schedule, penalties, and when bills are mailed.
Ways to lower your bill
- The $7,000 Homeowners' Exemption for owner-occupants (~$70/yr) — not the same as the homestead exemption, which protects home equity from creditors and changes no tax.
- Senior programs — Property Tax Postponement (62+, income-qualified; the state pays the bill at 5% simple interest) and a Proposition 19 base-year transfer (55+).
- A Proposition 8 decline-in-value review if the market drops below your assessed value.
- Appealing your assessment if it looks too high — the regular filing window in Sonoma County runs July 2 to November 30 (2026); only the assessed value can be appealed, not the rate or the flat charges.
Selling in Sonoma County: the transfer tax
A sale also pays a one-time documentary transfer tax of $1.10 per $1,000 of the price (net of any loan the buyer takes over) to the county (Revenue and Taxation Code §11911), $1,100 on a $1,000,000 sale. In Sonoma County, Petaluma, Santa Rosa add their own city transfer taxes on top. Estimate it for any sale with the California transfer tax calculator; the documentary transfer tax guide covers who pays and the exemptions.
Sonoma County property tax by city
Typical ad-valorem rate, assessed value and annual bill for the largest Sonoma County cities. Each city page has its own calculator and ZIP-level detail.
The city values are medians of single-family homes — the middle home in each city, while the county's average single-family value shown above ($607,376) is a mean across every single-family parcel in the county. A city can sit above or below that figure — the county average also includes the cities not listed here and the unincorporated areas, and the two come from different rolls (the county parcel file vs. BOE Table E1) — so the mean describes the county as a whole, not a typical home in any one city.
| City | Typical rate (most areas) | Median single-family value | Typical bill | Single-family parcels |
|---|---|---|---|---|
| Santa Rosa | 1.14%most areas 1.12–1.16% | $528,092 | $6,020 | 42,726 |
Rate = the middle (median) ad-valorem rate among the city's parcels, each at its own Tax Rate Area (county Auditor-Controller); "most areas" is the 10th–90th percentile range where it varies. Excludes Mello-Roos and fixed direct assessments. Assessed value = the median assessed value of the city's single-family parcels (county Assessor use codes) on the county roll for existing owners — a Proposition 13 basis, not a sale price. Typical bill = that value × the median rate: an illustrative figure for a middle-of-the-road parcel, not the median of actual bills; your bill depends on your own assessed value and Tax Rate Area. Single-family parcels = the parcels behind each median (county Assessor use codes). County aggregates only; verify with the county Assessor before relying on them.
Other Sonoma County cities (typical total rate in each city's most common Tax Rate Area): Petaluma 1.13%, Sonoma 1.12%, Rohnert Park 1.14%, Sebastopol 1.14%, Windsor 1.13%, Healdsburg 1.16%, Guerneville 1.12%, Cloverdale 1.11%, Forestville 1.13%, Cotati 1.14%, The Sea Ranch 1.07%, Cazadero 1.08%. Browse every city's Tax Rate Areas and their itemized bonds on what's in your Sonoma County property tax.
For every Sonoma County city and community with its typical rate, value and bill in one sortable table, plus a calculator for any city, see the Sonoma County property tax rate by city.
Sonoma County assessed value by city
The size of the property-tax base in each of Sonoma County's 9 incorporated cities: the total assessed value of all property inside the city limits on the 2025 roll, how fast it is growing, and its share of the county's $129.4 billion total. Dividing by each city's population shows how much taxable property stands behind each resident: from $396k in Sonoma down to $180k in Rohnert Park. About 41.1% of the county's assessed value lies outside any city, in unincorporated areas.
| City | Assessed value (2025 roll) | 1-year change | Since 2013 | Share of county | Per resident |
|---|---|---|---|---|---|
| Santa Rosa | $34.6 billion | +5.3% | +92.7% | 26.8% | $193k |
| Petaluma | $14.5 billion | +5.0% | +91.1% | 11.2% | $243k |
| Rohnert Park | $8.07 billion | +5.4% | +112.8% | 6.2% | $180k |
| Windsor | $5.69 billion | +4.2% | +84.8% | 4.4% | $220k |
| Healdsburg | $4.18 billion | +5.5% | +126.0% | 3.2% | $374k |
| Sonoma | $4.17 billion | +4.5% | +95.1% | 3.2% | $396k |
| Sebastopol | $1.82 billion | +6.3% | +79.0% | 1.4% | $242k |
| Cloverdale | $1.57 billion | +3.6% | +98.5% | 1.2% | $180k |
| Cotati | $1.56 billion | +4.4% | +88.9% | 1.2% | $212k |
Assessed value = the whole city's roll (homes, businesses, land and state-assessed utility property together) as reported by the Board of Equalization (Table 11), a Proposition 13 basis — not a typical home value, a tax rate or a bill. Growth reflects reassessment on sale, new construction, the annual inflation factor (capped at 2%), Proposition 8 decline-in-value cuts and their restoration, disaster losses, and any change in city boundaries. Share of county uses the county's total assessed value (Table 10); the two tables' bases differ slightly. Per resident divides the city's roll by its July 1, 2025 Census population estimate (Population Estimates Program, Vintage 2025); a high figure means a lot of commercial, industrial or second-home value per inhabitant, not a high tax bill. For a typical rate and bill, see the Santa Rosa table above; for the other cities use the county rate and the calculator above for your own estimate.
Neighboring counties' property tax rates
Sonoma County averages about 1.14%. Of the 5 counties that border it, 3 average less, 2 more:
Frequently Asked Questions
What is the property tax rate in Sonoma County?
Sonoma County's average property tax rate is about 1.14% of assessed value (California Board of Equalization, 2024-25) — the 1% Proposition 13 base levy plus each area's voter-approved debt. That's above the statewide average of about 1.11%. Your parcel's exact rate depends on its Tax Rate Area; Mello-Roos and fixed direct assessments, where they apply, are billed on top.
How much is property tax in Sonoma County?
Multiply your assessed value by about 1.14%. On a $500,000 assessed value that's roughly $5,695 a year. The county's average single-family assessed value is about $607,376 (Board of Equalization, 2025), which at the county's 1.139% average rate (BOE county average, 2024-25) works out to an implied bill near $6,918 a year for an existing owner. Under Proposition 13 your assessed value is generally what you paid when you bought, rising no more than 2% a year — use the calculator above for your own number.
When are Sonoma County property taxes due?
For 2026–27: the first installment is due Sunday, November 1, 2026 and must be paid by 5 p.m. Thursday, December 10, 2026; the second is due Monday, February 1, 2027 and must be paid by 5 p.m. Monday, April 12, 2027 (April 10 falls on a Saturday). Sonoma County had not published a 2026–27 mailing date when we last checked; every county must mail or e-mail the annual bill by November 1 (Revenue and Taxation Code §2610.5). The first installment is due November 1 and delinquent after December 10; the second is due February 1 and delinquent after April 10. A 10% penalty applies after each delinquency date. These deadlines are set by California state law (Revenue & Taxation Code §§2605–2606 and §§2617–2619) and are the same in every county; confirm the exact dates on your bill and the county tax collector's website.
How do I look up or pay my Sonoma County property tax?
Look up and pay on the Sonoma County Treasurer-Tax Collector's portal at sonomacounty.gov/acttc/pay-your-property-tax-bill-online — search by Assessor's Parcel Number (APN, printed on any prior bill) or, on most portals, by address; it shows both installments, penalties and payment history. Fees as the county publishes them: e-check free; card 2.34%. Not receiving a bill does not excuse a late payment (Revenue and Taxation Code §2610.5); look it up on the portal instead. The county has not announced a 2026–27 mailing date; by law bills go out by November 1. Every county's portal, fees and missing-bill number are on one page: californiapropertytools.com/california-property-tax-lookup-and-pay/#sonoma.
How can I lower my Sonoma County property tax?
Claim the $7,000 Homeowners' Exemption if you occupy the home; check the senior Property Tax Postponement and, if you're 55+, a Proposition 19 base-year transfer; if the market has fallen below your assessed value, request a Proposition 8 decline-in-value review; and appeal your assessment if it looks too high.
Official Sonoma County offices
Look up your parcel, exact rate, and bill directly with the county:
- Sonoma County Assessor — assessed value, exemptions, and parcel records.
- Sonoma County Auditor-Controller — the tax-rate book and Tax Rate Areas.
- Sonoma County Treasurer-Tax Collector — pay your bill and look up amounts due.
- Sonoma County GIS / parcel data — maps and downloadable parcel layers.
Learn More
Rate source: California State Board of Equalization county-average property tax rate (2024-25) — total ad-valorem levies divided by net assessed value. This is a county average; your parcel's rate depends on its Tax Rate Area, and Mello-Roos or fixed direct assessments are extra. Educational estimate, not an official bill — confirm figures with the Sonoma County Assessor and Treasurer-Tax Collector.