Understanding how property taxes work in California starts with recognizing that the system is built on two connected ideas: the county assessor's valuation of your property and the assessor parcel number, usually called the APN, that identifies it. This guide walks through the practical steps for both, from finding your APN to reviewing your assessment and, if needed, appealing it.

Step one is to locate your assessor parcel number. The APN is a unique identifier assigned by the county assessor to every parcel of land. It typically appears as a series of numbers separated by dashes, often in a format like 123-456-789, though the exact pattern varies by county. You can find it on your property tax bill, your annual notice of assessed value, your grant deed, or your title report from closing. County assessor websites also offer parcel search tools where you can look up an APN by address or owner name. Write the number down and keep it handy, because you will need it for nearly every step that follows.

Step two is to understand what the APN does and does not tell you. The APN identifies the parcel, not the house or the owner. It stays with the land even when ownership changes, and it is used by the assessor, the tax collector, and the recorder's office to track assessments, payments, and recorded documents. If you are buying property, confirm the APN on the listing, the title report, and the tax bill all match, since mismatches can signal a lot split, a lot line adjustment, or an error.

Step three is to review your assessed value. Under Proposition 13, your property's base year value is set when it changes ownership or undergoes new construction, and it can increase by no more than two percent per year, plus any value added by new construction. Each year the county assessor mails a notice of assessed value, usually in the summer, showing the assessed value for the coming tax year. Compare the assessed value on that notice with your purchase price and any improvements you have made. If the numbers seem inconsistent, gather your closing statement and building permits before calling the assessor.

Step four is to check the tax bill itself. The county tax collector issues the bill, usually in the fall, based on the assessor's roll. The bill lists the APN, the assessed value, the general tax rate of one percent, and any voter-approved bonds or special assessments for your area. Verify that the APN and address match your property and that the assessed value matches the assessor's notice. If something looks wrong, contact the assessor's office first, since the tax collector cannot change the assessed value.

Step five is to request an informal review if you believe the value is too high. Many counties allow you to call or submit a request for review before filing a formal appeal. Have your evidence ready: recent comparable sales, an appraisal, photos, and any documentation of damage or decline in value. The assessor may adjust the value without a formal hearing.

Step six is to file a formal appeal if the informal review does not resolve the issue. In most counties you file with the clerk of the assessment appeals board, generally between July 2 and November 30 for the regular roll, though supplemental assessments have different deadlines. Include your APN, the value you believe is correct, and your evidence. A hearing follows, and the board's decision can usually be appealed to the superior court.

Step seven is to pay your taxes on time regardless of any appeal. Unpaid taxes accrue penalties and interest, and an appeal does not pause the bill. Keep records of every notice, payment, and filing, and update your APN records whenever a parcel is split or combined.

A closer look is at the assessor notes.