How to Find Comparable Sales to Support a Property Tax Appeal

What are comparable sales in a property tax appeal?

Comparable sales — or "comps" — are recent, arm's-length sales of properties similar to yours in size, age, location, and condition, used to estimate what your home was actually worth on the assessor's valuation date. In a property tax appeal, comps are the primary evidence homeowners use to argue that their assessed value is higher than the market supports and should be lowered.

The logic is straightforward: your property is taxed based on an estimate of its market value. If several similar homes near you sold for less than your assessment, that is strong, objective evidence the assessment is too high. Assessors rely on mass-appraisal models that value thousands of properties at once, so individual homes are often mis-valued. Good comps let you show, property by property, where that estimate went wrong.

What makes a good comparable sale

Not every nearby sale is a useful comp. The closer a sale matches your property across the factors below, the harder it is for an assessor or review board to dismiss it.

Similar size and layout

Look for homes with close living area (finished square footage), a similar number of bedrooms and bathrooms, and a comparable lot size. Square footage is one of the strongest drivers of value, so a comp that is far larger or smaller than your home carries less weight unless you adjust for the difference.

Similar age and construction

A comp built around the same era as your home, with similar construction quality and materials, reflects comparable value. A brand-new build is rarely a fair comp for a decades-old house, even next door.

Similar location

Prioritize sales in your immediate neighborhood, ideally within the same subdivision, school attendance zone, or a short radius. Location captures many hard-to-quantify factors — school quality, walkability, noise, and desirability — so the closer the comp, the better.

Similar condition and features

Try to match condition (updated vs. original, well-maintained vs. deferred), plus major features like a garage, basement, pool, or recent renovation. A fully remodeled home is not a clean comp for one that needs work.

Recent, arm's-length sales

Use sales that closed close to your jurisdiction's valuation date — the specific date your assessment is meant to reflect, which is printed on or referenced by your assessment notice. Avoid non-market transactions such as sales between family members, foreclosures, or estate sales, since those prices may not reflect true market value.

Where to find recent sales data

You usually don't need to pay for data to find solid comps. Common sources include:

• Your county assessor or appraisal district website. Many jurisdictions publish a searchable property database showing recent sale prices, square footage, year built, and property characteristics. This is often the most authoritative source because it is the same data the assessor uses.
• County recorder or register of deeds. Recorded deeds and, in some areas, transfer-tax stamps document actual sale prices.
• Public real estate listing sites. Portals such as major national listing platforms show "recently sold" filters with photos, sale dates, and details that help you judge condition and features.
• A local real estate agent. Agents can pull comparable sales from the local Multiple Listing Service (MLS), often the most complete and current source. Many will provide a few comps at no charge.
• A licensed appraiser. For a higher-stakes appeal, a professional appraisal for your valuation date is the strongest single piece of evidence, though it comes at a cost.

When you gather a sale, record the address, sale date, sale price, living area, bed/bath count, lot size, year built, and condition or notable features. You'll need these to make apples-to-apples comparisons.

How to line comps up against your assessed value

Once you have candidate comps, the goal is to translate them into a defensible opinion of your home's value and compare it to your assessment.

1. Confirm your assessed value and valuation date. Read your assessment notice to find the assessed (or appraised) value and the date it reflects. Every comp should be evaluated against that same date.
2. Select your best 3 to 5 comps. Quality beats quantity. A handful of very close matches is more persuasive than a long list of loose ones. Drop any comp that differs sharply in size, age, or condition unless you can adjust for it.
3. Compare on a per-square-foot basis. Divide each comp's sale price by its living area to get a price per square foot, then apply that range to your home's square footage. This normalizes for size differences and is easy for a review board to follow.
4. Adjust for meaningful differences. If a comp has an extra bathroom, a finished basement, or a recent renovation you lack, reason down its value to reflect that your home is worth less than that comp — and vice versa. Keep adjustments modest and explainable.
5. Build a simple comparison grid. Put your property in one column and each comp beside it, with rows for address, sale date, price, square footage, price per square foot, beds, baths, and condition. A clean grid makes your case at a glance.
6. State your conclusion. Summarize what the comps indicate your home was worth on the valuation date, and how that figure compares to your current assessment. If the comps point clearly below your assessed value, that gap is the heart of your appeal.

Comparable-sales checklist

• [ ] I noted my assessed value and the valuation date from my notice
• [ ] Each comp is a recent, arm's-length sale (no family, foreclosure, or estate sales)
• [ ] Comps are close in living area (finished square footage)
• [ ] Comps are similar in age and construction quality
• [ ] Comps are in my neighborhood or a tight radius
• [ ] Comps match my home's condition and major features, or I adjusted for differences
• [ ] I calculated price per square foot for each comp
• [ ] I selected my 3 to 5 strongest comps
• [ ] I built a side-by-side comparison grid
• [ ] My comps point to a value at or below my assessment

Common mistakes to avoid

• Using current listings instead of closed sales. Asking prices are not evidence of value; only completed sales are.
• Cherry-picking only the lowest sales. Boards notice one-sided evidence. Present a fair, representative set of comps.
• Ignoring the valuation date. A sale from a very different market period may not reflect value on your assessment date.
• Comparing to dissimilar homes. A comp that is much larger, newer, or more renovated weakens your case unless clearly adjusted.
• Missing your deadline. Appeal windows are typically a set number of days from the date on your assessment notice, and they vary by state and county — check your own notice and local rules as soon as it arrives.

Comparable sales turn a subjective complaint ("my taxes feel too high") into an objective, evidence-based argument the assessor and appeal board are built to evaluate. Choose close matches, document them cleanly, and let the numbers make your case.