You budgeted for your mortgage and insurance, but what about Mello-Roos and that surprise “supplemental” bill that can show up after closing? If you are buying or selling in San Diego, understanding how property taxes really work can save you stress and money. You deserve clear answers you can use today. In this guide, you will learn how California’s rules set your tax base, how Mello-Roos districts add to carrying costs, and why supplemental bills arrive later so you can plan and negotiate with confidence. Let’s dive in.
How San Diego property taxes work
California’s Proposition 13 sets the foundation. Your property’s assessed value is usually the price you paid when you bought it. That value can increase up to 2% per year for inflation until there is another change in ownership or new construction that triggers a reassessment.
Your regular annual tax bill starts with a base rate of 1% of the assessed value. On top of that, your parcel may include voter-approved bonds, parcel taxes, and special assessments that vary by neighborhood. This is why your effective rate is often higher than 1% and why you should review the actual line items for your address.
In San Diego County, the Assessor sets your property’s assessed value, including any supplemental assessments. The Treasurer-Tax Collector issues the tax bills, manages payments, and handles delinquencies. If you need parcel-specific details, your current tax bill and county parcel lookup tools are the best sources.
Key dates and payment schedule
California’s property tax year runs from July 1 through June 30. The first installment is due November 1 and becomes delinquent after December 10. The second installment is due February 1 and becomes delinquent after April 10.
Penalties apply after the delinquency dates. If you use an impound account, your lender usually pays by these deadlines, but you should still track due dates and confirm that payments post on time.
Mello-Roos explained
Mello-Roos, also called Community Facilities Districts or CFDs, fund public improvements like roads, parks, schools, and safety services, often in newer developments. Voters inside a CFD approve a special tax that is levied on properties within the district.
Most Mello-Roos charges appear as separate line items on your annual secured property tax bill. In many cases, lenders include these amounts in your impound account since they are billed along with your regular property taxes.
There is no single formula for Mello-Roos. Some CFDs charge a fixed dollar amount, others tier rates by lot size or home type, and some use a percentage-based approach. Many CFDs support bonds that last 20 to 40 years. Some districts keep a smaller annual charge for ongoing services even after bonds are retired.
What matters to you is that the CFD tax is tied to the property, not the owner. Unless the bonds are prepaid and the district allows it, the charge remains with the parcel and transfers to the next owner.
How Mello-Roos impacts your budget
Mello-Roos can add a few hundred to several thousand dollars per year to your carrying costs. The exact amount depends on the district and the property. Because this cost is significant, verify if a home is located in a CFD before you write an offer, and build the annual amount into your monthly budget.
To check for Mello-Roos on a specific property, you can:
- Review the seller’s most recent property tax bill for CFD line items.
- Confirm the parcel number and use county parcel lookup tools to view the current bill.
- Review the preliminary title report and seller disclosures, which must identify special assessments.
- Ask for any available CFD formation documents if you need to understand maximum possible rates and terms.
Supplemental tax bills after you buy
A supplemental assessment is triggered when the Assessor sets a new value mid-year because of a change in ownership or new construction. This is separate from your regular bill and it often arrives weeks or months after closing.
The supplemental bill covers the difference between taxes based on the old assessed value and taxes based on your new assessed value for the remainder of the fiscal year. The county prorates it based on the date your deed recorded or the date new construction was completed.
Conceptually, the calculation works like this:
- Supplemental tax = (New assessed value − Old assessed value) × Total tax rate × Portion of fiscal year remaining.
Here is an illustrative example to show the math, not a quote. If the old assessed value was 400,000 dollars and your new value after purchase is 700,000 dollars, the difference is 300,000 dollars. If the combined rate is 1.1% and your closing was August 1, covering 11 out of 12 months, the estimated supplemental would be about 300,000 × 1.1% × 11⁄12, which is roughly 3,025 dollars for that fiscal year remainder. Your actual bill will reflect your property’s exact rates and days.
Who pays the supplemental bill
Legally, the owner of record going forward is responsible for the taxes on the property, which includes supplemental bills after a sale. In practice, payment responsibility is negotiated in the purchase contract.
Many contracts prorate only the regular annual taxes at closing and leave supplemental bills to the buyer unless the agreement says otherwise. If you want the seller to contribute to expected supplemental taxes from the sale, put that in writing. You can also request an escrow holdback or a credit if the bill will not arrive until after closing.
Buyer checklist to estimate carrying costs
Use this quick process to avoid surprises and budget with confidence:
- Gather documents
- Ask the seller for the most recent property tax bill. Confirm the Assessor’s Parcel Number, or APN, so you can verify current charges.
- Confirm the combined tax rate
- The base rate is 1% of assessed value. Add the parcel’s voter-approved bonds, parcel taxes, and special assessments listed on the bill to reflect the actual combined rate.
- Identify any Mello-Roos/CFD line items
- Note the annual amount for the parcel. If the property is in a CFD, include that in your monthly mortgage budget.
- Estimate annual property tax
- Multiply the estimated assessed value at purchase by the combined rate for an annual total. Divide by 12 for a monthly estimate.
- Estimate supplemental exposure
- If your purchase price is much higher than the seller’s current assessed value, estimate the supplemental using the conceptual formula. Discuss with your agent whether to request a credit or holdback.
- Confirm escrow impounds
- Ask your lender if taxes and assessments are included in your impound account. Most lenders pay the items that appear on the secured bill. Mid-year supplemental bills may require separate handling.
Seller checklist and smart prep
- Provide your current property tax bill and disclose all known special assessments.
- Expect that your sale will trigger a supplemental assessment. Decide whether you are willing to credit the buyer or agree to an escrow holdback for the expected amount.
- If you plan any additions or improvements before closing, understand that new construction can trigger reassessment. Talk with your agent before starting projects close to the sale date.
Negotiation tips for supplemental taxes
- Make it explicit. If you want the seller to pay any supplemental taxes from the change in ownership, write it into the purchase agreement.
- Consider a holdback. If timing is tight and the bill will arrive after closing, a reasonable escrow holdback can protect both sides.
- Use real numbers. Base your negotiation on the actual combined rate and the expected value change, not rules of thumb.
Red flags to watch
- Big price jump over the seller’s assessed value. A much higher sale price often means a large supplemental bill.
- Newer communities with CFDs. Substantial Mello-Roos amounts are common in newer neighborhoods and master-planned areas.
- Recent new construction. A new build or major permitted remodel can trigger a supplemental assessment tied to the improvement.
VA and PCS-friendly planning
If you are using a VA loan or planning a PCS, clear tax planning protects your BAH-driven budget. Confirm whether your lender will impound taxes and special assessments so your monthly payment is predictable. Build the parcel’s combined rate and any Mello-Roos into your affordability check before you write an offer.
For supplemental bills, plan a small post-closing reserve if your purchase price is well above the prior assessed value. If timing matters for your PCS move, consider negotiating a credit or holdback so you are not hit with a large surprise after you have transferred.
Bottom line for San Diego buyers and sellers
- Your base property tax rate is 1% of assessed value, but local bonds and assessments increase the total.
- Mello-Roos are district special taxes that can materially affect your annual costs. Verify them before you make an offer.
- Supplemental bills arrive after a sale or new construction and are prorated for the remainder of the year. Decide upfront how you will handle them in your contract.
If you want a clear, VA-savvy plan tailored to your address and budget, let’s talk. Schedule your free consult with Alanna Strei to map your tax, Mello-Roos, and supplemental strategy before you make your next move.
FAQs
How much are San Diego property taxes for a typical home?
- The base rate is 1% of assessed value, and your parcel’s total includes voter-approved bonds and special assessments, so always check the current tax bill for the exact combined rate.
What are Mello-Roos and how much do they add?
- Mello-Roos are special taxes in Community Facilities Districts that fund infrastructure and services, and they can range from a few hundred dollars to several thousand dollars per year depending on the district and property.
Who pays the supplemental tax bill after a home sale?
- The owner of record is responsible going forward, but payment is typically negotiated in escrow, so include clear language if you want the seller to pay any supplemental taxes from the change in ownership.
Can refinancing remove Mello-Roos from my bill?
- No, Mello-Roos are attached to the parcel, not the loan, and prepaying bonds is only possible if the district allows it and you pay the required principal and costs.
Will my lender pay supplemental bills through my impound account?
- Lenders usually pay the line items on the secured annual bill, but supplemental bills that arrive mid-year may require separate handling, so ask your lender how they manage supplemental payments.
When are property tax payments due in San Diego County?
- The first installment is due November 1 and delinquent after December 10, and the second installment is due February 1 and delinquent after April 10, with penalties after those dates.
