How do I estimate property taxes before making an offer?

by Alessandra Imanabadi

By Alessandra Imanabadi · Nationwide Fine Homes

Use the property’s tax details and your expected assessed value—not the seller’s current annual bill.

An owner who bought decades ago may have a much lower assessed value. A purchase generally triggers reassessment to current market value, commonly reflected by the purchase price unless the assessor determines otherwise.

Start with the base, then investigate the additions

California’s base property-tax rate is 1% of assessed value. Voter-approved debt and fixed assessments can add to that amount. Some newer communities have Mello-Roos or other charges that materially affect the total.

I sometimes use 1.25% as a preliminary planning illustration—not a universal Bay Area rate. At that assumed total, a $1.5 million home would mean $18,750 annually, or $1,562.50 monthly. The actual property may differ.

Review the current bill for the rate structure and individual assessments, then estimate the effect of the new assessed value. Copying the seller’s total skips the most important step.

Prepare for supplemental bills

A supplemental assessment addresses the change in value for the applicable period. The bill can arrive separately from the regular tax bill. Do not assume the mortgage escrow account will automatically pay it; confirm with the servicer and county.

Eligible tax-base transfers may also change the calculation, so identify that possibility before relying on a standard estimate.

Your agent should help assemble the property information; the assessor and loan servicer confirm their respective calculations and payment handling.

I would be pleased to help you understand those details early in the search. You can then judge the payment with a fuller picture of what ownership will cost.