For many Los Angeles County homeowners, the question ahead of October property tax bills is straightforward: Why does a tax assessment sometimes come in far below what a home could sell for, and when can that bill be reduced?

That question is especially relevant in Pasadena and Altadena, where some homeowners may still pay taxes based on long-held Proposition 13 values, while others could qualify for temporary relief if their home's market value has dropped.

Here's what to know

As Pasadena Now reported, the Los Angeles County Assessor's Office explained in its September newsletter that, because of Proposition 13, a home's taxable value often does not match what it could fetch in a sale.

Assessments generally follow the lower of two figures. One is the property's Jan. 1 market value. The other is its factored base-year value, which is usually set when the property changes hands and can rise by no more than 2% a year. That explains why a house owned for many years may be assessed far below an estimated sale price.

Big swings in assessed value usually happen only with a new owner, new building work, or a temporary Proposition 8 decline-in-value adjustment. That adjustment lowers an assessment when a home's Jan. 1 market value slips below its base-year value, and the assessment can climb back as prices rebound, though never past the base-year amount.

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More background

Owners who think their home was worth less on Jan. 1 than its base-year value can ask for a decline-in-value review. The request goes on Form RP-87, which owners can file online on the assessor's website between July 2 and Nov. 30 each year.

The office said a drop in value alone isn't enough. Any reduction is temporary and gets reviewed each year, and neither lost equity nor a price below what the owner paid qualifies on its own. What matters is whether the home's market value on Jan. 1 fell below its Proposition 13 value.

The newsletter used wildfire recovery as an example, pointing to inherited homes whose title and assessor records were never updated. In some cases, those outdated records made it hard to pinpoint who owned a home and who qualified for certain disaster relief.

Assessor Jeff Prang made a similar point to Pasadena officials after the Eaton Fire. "Accurate property records matter," his office wrote.

What can be done?

Keeping deeds and ownership records up to date could prevent complications during emergencies. Homeowners may be able to reduce a tax bill by filing Form RP-87 before Nov. 30 if their property's Proposition 13 value is still higher than what it was Jan. 1.

Property taxes aren't the only household expense worth a second look. With Palmetto's help, the average Southern California resident can save 40% on their electric bills, which can add up to thousands of dollars per year. The special offer gives eligible homeowners a way to cut another major household expense with $0 down.

Where can I learn more?

Housing costs and property taxes are making headlines elsewhere, too.

• In Palo Alto, assessed property values are rising as homeowners file more appeals.

• In Jackson County, Missouri, tax credits for homeowners followed widespread complaints about overpaid assessments.

• Across the U.S., rising home insurance costs are pushing property values lower in exposed areas.

• In Redwood City, California, rent cap and tenant protections advanced to voters.

• Nationwide, tax incentives for home renovations are driving interest in solar upgrades.

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