Comparable Sales: The Core Evidence for a Tax Appeal

Start with the value date

Find the valuation date, also called the assessment date, on your notice or on the assessor website. That date tells you which market period matters, and a sale that happened after the value date may be less useful to you or may not be allowed under local rules.

California's assessment appeal FAQ says that sales closest in time to the valuation date are usually better indicators of value, and it also explains that comparable sales more than 90 days after the assessor's value date may not be considered by an appeals board. Other places use different rules, so confirm the local standard before you rely on a sale.

Once you have the value date, start with the same property type, because mixing types can weaken your argument when the market values them differently. Compare a single-family house only to other single-family houses, a condo only to other condos, and a townhouse only to other townhouses. From there, compare the basic property facts, since a home with major updates, a larger lot, or a better location may sell for more for reasons that do not apply to your property.

Compare these basic facts between your property and each sale:

• Living area
• Bedroom count
• Bathroom count
• Lot size
• Year built
• Garage
• Basement
• Condition
• Renovations
• Location

Stay close in location, and begin inside the same neighborhood, subdivision, condo building, school zone, or tax area when possible. If there are not enough sales nearby, expand your search slowly and explain why it had to move outward. Distance matters because local streets, schools, traffic, the condition of nearby homes, access to services, and local demand can all affect sale price, so a sale two blocks away may be stronger than a sale two miles away when the properties are otherwise similar.

Use sold properties rather than asking prices. A listing price is what a seller asks, while a sale price is what a buyer actually paid, and appeal offices usually care more about completed sales because a completed sale shows real market activity. If you use a listing only as context, label it as a listing and do not present it as a completed comparable sale. When the local office has an official sales search, start there, since official records are easier to verify.

Build a simple comparable sales table

Build a table with one line for your property, called the subject property, and one line for each comparable sale. Keep the columns basic, and include the address, sale date, sale price, living area, beds, baths, year built, lot size, distance, a condition note, and price per square foot if that is useful. Below each sale, write one sentence explaining why it is similar or why an adjustment may be needed. For example, you might write that a sale is in the same subdivision and a similar size, but that it has a finished basement while your subject property does not.

Avoid weak comparable sales, and do not rely on a sale only because the price helps your argument, because a weak sale can make your appeal file easier to dismiss.

Watch for sales that are weak because the property has one of these issues:

• A different style
• A different school zone
• A much larger lot
• Major renovations
• Foreclosure status
• A family sale
• A distressed sale
• Missing details

If your property has a condition issue, add photos and repair records, and if the property record lists the wrong facts, fix those facts first. Your value argument gets stronger when the record facts and the market evidence support the same conclusion.

How many comparable sales to start with

Start with three to five possible sales, and use your best matches first. More sales can help if they are strong, but too many weak sales can create confusion.

If the local appeal form asks for a specific number or format, follow that instruction, because some locations require a comparable sales form or specific evidence upload steps. New Jersey, for example, uses a separate comparable sale form as part of its appeal process.