About Castellan
Your property deserves a stronger case.
Castellan is a San Francisco-based tech company building the technology for smarter, more effective property tax appeals. We combine cutting-edge artificial intelligence and data analysis with insights from veteran tax experts to turn property and market data into compelling cases for lower taxes.
Our appeals typically deliver a property tax reduction of 15 to 40% on the cases we take and win. We handle everything end-to-end, from analysis to hearing, making a complex process effortless for property owners.
Typical property tax reduction
on the cases we take and win.
A stronger appeal starts with better evidence. We build each case around the property and market data that support it.
This is the range we see on appeals we take and win. Individual results vary; it is not a guarantee of future savings.
Better technology. Stronger property tax appeals.
Your property is specific. Its tax assessment should reflect that. We started Castellan with a simple belief: property owners deserve a careful, well-supported case for what their property is worth.
That means looking closely at the records, finding the evidence that matters, and turning it into a clear argument. We bring the precision of technology and the judgment of experienced tax experts to that work.
We’re building technology that turns complex property data into a clear path forward, making it easier for owners to challenge an assessment with confidence.
Technology does the deep work.
Expertise gives it direction.
Better appeals come from the details. Our approach brings them together into a case that is clear, specific, and supported by evidence.
Analysis with depth
Our technology examines assessment records, comparable properties, and market evidence to identify where a valuation deserves a closer look.
Advised by veteran tax experts
Experienced tax experts inform our approach, helping us focus the analysis on the details that make a property tax appeal compelling.
A case built around your property
We connect the evidence into a focused argument for your property’s value, then handle the appeal from preparation and filing through the hearing.
A complex process, handled from start to finish.
See how our pricing worksEverything, end-to-end
We handle the research, prepare the evidence, file the appeal, and represent your case at the hearing. You get a single team responsible for the entire process.
Our success is tied to yours
There is nothing to pay up front. Our appeal fee is a share of your savings, charged only if we win a reduction. You see the terms in writing before signing.
Clarity from the start
If the evidence doesn’t support an appeal, we tell you. Our job is to build a sound case and make the process easier to understand.
Let’s take a closer look
at your property taxes.
Start with a free analysis. We’ll check the evidence and show you where your property stands.