Prop 19 Explained For San Carlos Homeowners

Thinking about selling in San Carlos, downsizing nearby, or helping family with an inherited home and wondering how Prop 19 affects your property taxes? You are not alone. The 2020 voter‑approved law changed how you can move your low taxable value to a new home and how children can keep a parent’s tax base. In this guide, you will see what changed, who qualifies, how the math works in plain English, and the exact steps to file in San Mateo County. Let’s dive in.

What Prop 19 changed

Proposition 19 updated two big parts of California property‑tax law. First, it expanded base year value transfers, sometimes called portability, for eligible homeowners moving to a new primary residence. Second, it narrowed the parent‑to‑child and grandparent‑to‑grandchild exclusions from reassessment.

At a high level, if you qualify to transfer your base value, you may move it to a replacement home anywhere in California. For inheritance, the exclusion now generally applies only when the child makes the home a primary residence and it is limited in amount. County Assessors implement the rules and process the claims.

For statewide rules and FAQs, review the California State Board of Equalization’s Prop 19 page at the BOE website. For local filing, the San Mateo County Assessor is the authority for San Carlos properties.

• Statewide overview and FAQs: California State Board of Equalization Prop 19
• Local filing and forms: San Mateo County Assessor
• Background and ballot analysis: Legislative Analyst’s Office on Prop 19

Who qualifies for base value transfers

You may be eligible if any of the following apply:

• You are age 55 or older.
• You are a severely disabled homeowner.
• Your home was made uninhabitable by a qualifying disaster or hazard.

Your current home must be your principal residence, and your replacement home must become your principal residence. You can use this benefit up to three times per eligible person, with additional transfers possible for certain disaster situations.

How base value transfers work

Your base year value is the assessed value the county uses to calculate your property taxes. In San Carlos, market values are often far above long‑held assessed values, so portability can meaningfully lower the assessed value of your next home compared with a full reassessment.

If your replacement home is lower in value than the one you sold, you generally carry your old taxable base to the new home. If your replacement home is higher in value, you keep your old base but are reassessed for the difference.

Always file a claim with the county assessor to receive the benefit. The county verifies eligibility and calculates any supplemental assessment.

Example: Downsizing within San Mateo County

Alice, age 62, lives in San Carlos. Her taxable base is $300,000, while her home’s market value is much higher. She sells and buys a smaller home in Belmont for less than her San Carlos sale price.

Under Prop 19 portability, Alice may transfer her $300,000 base to the Belmont home. Without portability, her assessed value would reset to the Belmont purchase price, which could be much higher. With the transfer, her assessed value remains closer to $300,000, lowering her ongoing property taxes relative to a full reassessment.

Example: Moving to a more expensive home elsewhere in California

Carol, age 66, owns a San Carlos home with a taxable base of $400,000. She buys a replacement home in Sacramento for $900,000. Because the replacement is more expensive, Carol keeps her $400,000 base and is reassessed for the difference between the homes’ values.

In practical terms, her new assessed value will be higher than $400,000 but lower than a full reassessment at $900,000. An ineligible buyer of the same Sacramento home would be assessed at the full purchase price.

What this means for your monthly costs

Property tax is calculated on assessed value. Preserving a lower base year value can materially reduce your yearly taxes in high‑value markets like San Carlos. If you buy a higher‑priced replacement, you still benefit because only the difference is added to your transferred base rather than starting over at the full purchase price.

Parent‑to‑child transfers after Prop 19

Prop 19 narrowed the reassessment exclusion for transfers from parent to child or grandparent to grandchild. Today, the exclusion generally applies only if the property becomes the child’s principal residence and it is limited in how much assessed value can be retained.

Transfers of second homes or investment properties are typically reassessed at market value. This is a significant change for families with multiple properties in high‑value areas like San Carlos.

Example: Inheriting a San Carlos home

A parent’s San Carlos home has a taxable base of $300,000 and a market value at the date of transfer of $2,500,000. If the child moves in and makes it their principal residence, the child can retain the parent’s taxable base for a portion of the value up to the statutory allowance. Any amount above that threshold is reassessed.

If the child does not make the home their principal residence, the property is reassessed at market value. That reassessment can cause a large increase in property taxes compared with the inherited taxable base.

How to file in San Mateo County

The San Mateo County Assessor administers all Prop 19 claims for San Carlos properties. You must file to receive benefits. The assessor will verify eligibility, determine the assessed value, and issue any supplemental bills or credits.

What to file and typical documents

• Completed claim forms for a base year value transfer or parent‑to‑child exclusion.
• Recorded deed and closing statements showing sale and purchase details.
• Proof of eligibility, such as age or disability documentation if applicable.
• Proof of principal residence for the replacement home or for the inheriting child, such as driver’s license or voter registration.
• For inheritances, a death certificate and trust or probate documents.

Check the county assessor’s site for current forms and instructions.

Deadlines and processing timeline

Claims are not automatic, so submit your filing as soon as you close or inherit. Deadlines can apply based on the date of transfer, completion of new construction, or occupancy. Filing promptly helps avoid delays and unexpected supplemental bills.

About supplemental assessments

Even with an approved transfer, you may receive interim supplemental bills while the county processes your claim. Ask the assessor how adjustments and credits will be handled once your claim is finalized.

When to consult a professional

Consider speaking with a CPA or property‑tax attorney if any of the following apply:

• You are planning a complex estate or trust transfer.
• There is a large gap between market value and your current taxable base.
• You are moving out of county or buying a much higher or lower priced replacement.
• You expect to claim disability or disaster qualifications.

A professional can model outcomes, explain likely reassessments, and coordinate timing.

Why Prop 19 matters in San Carlos

San Carlos and the mid‑Peninsula are high‑value markets. The dollar impact of keeping a long‑held taxable base can be significant compared with a full reassessment. If you plan to downsize locally, move closer to family elsewhere in California, or transfer a family home, understanding Prop 19 can help you align your housing goals with a tax‑smart plan.

If you are weighing a sale, buy, or family transfer, you will get the best outcome when you combine a clear tax strategy with disciplined pricing, preparation, and negotiation. That is where a local, data‑driven advisor adds value.

Ready to map your next move or run scenario planning tailored to your property and timeline? Connect with Wendy Kandasamy to coordinate your sale or purchase and align the process with your Prop 19 strategy.

FAQs

Who can transfer a base year value under Prop 19?

• Homeowners who are 55 or older, severely disabled, or whose home was made uninhabitable by a qualifying disaster, provided both the sold and replacement properties are or become principal residences.

Can I transfer my base value from San Carlos to any county?

• Yes. Inter‑county transfers are allowed anywhere in California if you meet eligibility and principal residence requirements.

How many times can I use portability benefits?

• Generally up to three times per eligible person, with additional transfers possible for certain disaster‑related moves. Confirm details with the county assessor.

What happens if my replacement home costs more than the one I sold?

• You keep your old base and are reassessed for the difference, so your new assessed value will be higher than your old base but lower than a full reassessment at the purchase price.

Do I have to live in the replacement home full time?

• Yes. The replacement must become your principal residence. For parent‑to‑child exclusions, the child must also make the home a principal residence to qualify.

Can children keep a parent’s tax base on an inherited San Carlos home?

• Only if the child makes the home a principal residence and subject to a limit on the amount of assessed value that can be retained. Amounts above the allowance are reassessed.

Does Prop 19 affect special assessments or Mello‑Roos?

• Portability affects assessed value for general property tax. Special assessments, parcel taxes, and Mello‑Roos typically remain attached to the property and may still apply.

Where do I file and what if I miss a form?

• File with the San Mateo County Assessor. Claims are not automatic, so missing forms can lead to higher assessments or delays. File promptly and confirm receipt with the assessor.