Buying a home in San Rafael is exciting, but the property tax piece can feel confusing. You want to know what you will owe, when you will owe it, and how to budget so nothing catches you off guard. The good news is California’s rules are clear once you break them down. In this guide, you will learn how Prop 13 sets your baseline, why a reassessment happens when you buy, how supplemental bills work, what local parcel and special assessments can add, and how lenders set up impounds so your monthly payment stays on track. Let’s dive in.
Property tax basics in California
Prop 13 and your base‑year value
Under California’s Prop 13, the ad valorem portion of your property tax rate is limited to 1% of your assessed value plus any voter‑approved local taxes and assessments. When you buy, your assessed value generally resets to your purchase price. That new base‑year value can rise by no more than 2% per year while you own the home, unless there is new construction or another reassessment event. This structure keeps the 1% portion stable and adds locally approved charges as they apply to your parcel.
What “combined rate” really means
Your tax bill will show more than just 1%. Marin County adds voter‑approved parcel taxes, bonds, and special assessments to fund services like schools, fire protection, open space, and local infrastructure. The result is a combined rate that is often around 1.0% to 1.5% in many Bay Area communities, depending on the property and its local measures. The exact combined rate for a specific San Rafael parcel appears on that parcel’s tax bill.
Local levies you may see in San Rafael
- Voter‑approved parcel taxes and bonds
- Special or benefit assessments for items such as lighting, landscaping, stormwater, or sewer
- Community Facilities District (CFD or “Mello‑Roos”) taxes in some developments
- Countywide assessments for services like flood control or mosquito abatement
- HOA dues are separate from the property tax bill, but they affect your monthly budget
When your home gets reassessed
What triggers reassessment
A sale typically triggers reassessment to your purchase price, which becomes the new base‑year value. New construction can also trigger a reassessment of the new construction portion. Some transfers are excluded, such as certain transfers between spouses and some parent‑child transfers that meet limits under current law. If you think an exclusion may apply, the Marin County Assessor can confirm details.
How Prop 19 can affect transfers
Prop 19 changed rules starting in 2021. It tightened the parent‑child exclusion and expanded base‑year value transfers for eligible homeowners, including seniors, people with disabilities, and wildfire or disaster victims, subject to specific limits and rules. This matters if you are replacing a primary residence or handling a family transfer. For parcel‑specific guidance, check with the Marin County Assessor.
Regular vs. supplemental tax bills
What happens after you close
California’s property tax year runs July 1 through June 30, and regular bills are typically mailed in October. When your purchase triggers a reassessment, Marin County will also issue a supplemental assessment reflecting the difference between the new and old assessed values, prorated for the portion of the fiscal year remaining after your closing date. The supplemental bill arrives separately from the regular bill and can come weeks or months after you move in.
How the supplemental amount is calculated
Conceptually, the county calculates your supplemental tax as:
- Supplemental tax = (New assessed value − Prior assessed value) × Combined tax rate × (Days remaining in fiscal year ÷ 365)
The next regular bill, mailed in October, will show the full year of taxes at your new base‑year value.
Billing cycle and common due dates
California norms you should know:
- Fiscal year: July 1 to June 30
- First installment: due November 1, delinquent December 10
- Second installment: due February 1, delinquent April 10
- Supplemental bills: payable according to the county’s supplemental billing schedule, often upon receipt
Confirm Marin County’s exact timing and payment instructions with the Treasurer‑Tax Collector. Because supplemental bills are separate, they can surprise new owners who do not plan ahead.
Impounds and your monthly mortgage budget
How lender impounds work
When you have a mortgage, your lender may require an escrow, also called an impound account, to collect monthly amounts for property taxes and homeowners insurance. The lender estimates your annual totals, divides by 12, and adds that amount to your mortgage principal and interest. Federal rules allow lenders to keep a small cushion, so your initial impound deposit at closing may be higher than a single month’s share.
What lenders include or exclude
Lenders usually escrow for statutory property taxes and homeowners insurance. Whether parcel taxes, special assessments, or CFD taxes are included varies by lender and whether those charges appear on the county tax bill. Some special assessments are billed separately and might not be escrowed. Always ask your lender to spell out what is included in the escrow calculation.
Practical budgeting tips
- Budget for your monthly tax impound, insurance impound, and any HOA dues
- Identify any special assessments that are billed outside the county tax bill and set funds aside
- Plan for a supplemental bill after closing if your assessed value increased
- Ask your lender and escrow officer for a written breakdown of your initial escrow deposit and monthly impound payments before you sign
Step‑by‑step: estimate your first‑year taxes
Use this simple framework to estimate your annual and supplemental taxes for a San Rafael purchase. These steps are for planning only. For exact amounts, use the parcel’s actual combined rate and assessed values from Marin County records.
Find the prior assessed value (PA) for the parcel in Marin County records.
Use your purchase price as the new assessed value (NA) for a typical change of ownership.
Estimate your regular annual tax: NA × Combined tax rate. The combined rate includes the 1% ad valorem portion plus local levies shown on the tax bill.
If you close during the fiscal year, estimate a supplemental bill:
- Tax difference = NA − PA
- Supplemental amount = Tax difference × Combined tax rate × (Days remaining in fiscal year ÷ 365)
Estimate your monthly tax impound by dividing the annual tax by 12. Add your homeowners insurance impound if required.
Remember the timing: you may receive a prorated amount at closing, then a supplemental bill after close, and the next October bill will reflect a full year at your new base‑year value.
Example scenarios for San Rafael buyers
These examples use a hypothetical combined rate of 1.12% for illustration only. Replace the rate and values with the numbers on your parcel’s actual tax bill.
Example A — Purchase price $600,000; prior assessed value $400,000; combined rate 1.12%.
- Annual tax at NA: $600,000 × 0.0112 = $6,720
- Monthly tax impound (tax only): $6,720 ÷ 12 = $560
- If you close on May 1 with about 61 days left in the fiscal year:
- Tax difference: $200,000
- Supplemental: $200,000 × 0.0112 × (61 ÷ 365) ≈ $375
- Expect the regular October bill to show the full $6,720 for the next tax year.
Example B — Purchase price $1,200,000; prior assessed value $800,000; combined rate 1.12%.
- Annual tax at NA: $1,200,000 × 0.0112 = $13,440
- Monthly tax impound (tax only): $13,440 ÷ 12 = $1,120
- If you close on March 15 with about 108 days left:
- Tax difference: $400,000
- Supplemental: $400,000 × 0.0112 × (108 ÷ 365) ≈ $1,326
- Your October bill will reflect the full $13,440 for the next tax year.
Example C — Purchase price $2,000,000; prior assessed value $1,000,000; combined rate 1.12%.
- Annual tax at NA: $2,000,000 × 0.0112 = $22,400
- Monthly tax impound (tax only): about $1,867
- If you close on June 1 with about 30 days left:
- Tax difference: $1,000,000
- Supplemental: $1,000,000 × 0.0112 × (30 ÷ 365) ≈ $918
- Large jumps in assessed value can increase your escrowed monthly payment. Confirm the lender’s cushion requirements.
What to review before and after closing
Before you make an offer:
- Ask for the most recent property tax bill and any known parcel taxes or bonds
- Look up the prior assessed value and itemized levies for the parcel
During escrow:
- Confirm how regular tax prorations will be handled at closing
- Ask your lender for a written estimate of monthly impounds and the initial escrow deposit
- Review the preliminary title report for any recorded assessments or special taxes
After closing:
- Watch for a supplemental assessment and bill if your purchase triggered a reassessment
- Confirm who pays any supplemental bill per the purchase contract and escrow instructions
- Keep copies of all notices and bills from Marin County
Final thoughts for San Rafael buyers
If you understand the base‑year reset under Prop 13, how local levies increase the combined rate, and when supplemental bills arrive, you can budget your first year with confidence. Pull the parcel’s current tax bill, confirm the combined rate, and work through the steps above with your lender and escrow team. A few careful checks now will help you avoid surprises later.
Buying in San Rafael should feel exciting, not stressful. If you want help reading a tax bill, planning for impounds, or aligning your budget with neighborhoods and home types across Marin, connect with Jennifer Bowes for local guidance tailored to your goals.
FAQs
How does Prop 13 affect my San Rafael tax bill?
- Prop 13 sets the ad valorem rate at 1% of your assessed value and limits annual assessed value increases to no more than 2% while you own the home, plus voter‑approved local levies.
What is a supplemental tax bill after I buy a home?
- A supplemental bill reflects the difference between your new assessed value and the prior assessed value, prorated for the remainder of the fiscal year after your closing date, and it arrives separately.
When are Marin County property taxes due for homeowners?
- Regular bills are typically mailed in October with installments commonly due November 1 and February 1, becoming delinquent on December 10 and April 10; verify exact dates locally.
Will my lender escrow for parcel taxes and special assessments?
- Lenders usually escrow statutory property tax and insurance, but inclusion of parcel or special assessments varies; ask your lender to confirm what is included in your impounds.
How do I estimate my first‑year property taxes in San Rafael?
- Use your purchase price as the new assessed value, apply the parcel’s combined rate from the tax bill, and add any prorated supplemental amount based on your closing date within the fiscal year.
Can Prop 19 help me transfer my tax base to a new home?
- Prop 19 may allow eligible homeowners to transfer a base‑year value to a replacement home, subject to rules and limits; confirm details with the Marin County Assessor.
