How this works

This page explains, in plain terms, how the report on your property is built. Nothing here is an appraisal or legal advice. Every number comes from public records published by your county assessor.

County value

In Washington, the assessor values every property each year at what it would sell for on January 1 of the assessment year. That value is used to compute the next year's property tax. Clark County publishes those values for every parcel, going back to 2008, in a public data file that is refreshed monthly. We use the market value the county assigned, never the taxable value, because the taxable value is lowered for exempt properties and for owners in the senior or disabled program, which would make comparisons unfair.

Similar homes

To decide whether your value is in line, we compare you with homes that the assessor would also treat as comparable:

We never include your own home in the group. If fewer than 40 homes match, we widen the rules one step at a time, in this order: year built within 20 years; quality within two grades; size within 35%; then the nearest neighborhoods. The report always says which step was reached, and you can change the rules yourself.

Why this order: once quality is held fixed, value per square foot depends only weakly on age, so widening the year band changes little. Size is widened last because small homes carry a higher value per square foot than large ones, so a loose size band would distort the comparison.

Where you stand

We compare value per square foot of living area, which removes most of the effect of size. We then say how many of every 100 similar homes have a lower value per square foot than yours. The arithmetic is done on logarithms with the median and the median absolute deviation, which are not thrown off by a few unusual homes.

Small groups are noisy, so we also show a range: we re-draw the group of similar homes a thousand times with replacement (a bootstrap) and report where your position lands 90% of the time. A wide range means the position is uncertain. Groups under 40 homes are marked "small group"; under 15 we do not quote a position at all.

The verdict is deliberately conservative. We say "higher than most" only when the whole range sits above the top quarter, and "lower than most" only when it sits below the bottom quarter. Otherwise your value is "in line".

Growth

For growth we use the full history of values since 2008. We compare the percentage change in your value with the change for homes in the same assessor neighborhood, the same inspection cycle (see below) and the same kind of home. Growth in percent is far less sensitive to size and quality than the value itself, so the growth group is larger than the "similar homes" group.

Homes that changed physically are left out of the comparison for the years affected: homes built or effectively rebuilt after the start of the window, and homes whose building value jumped by more than half in a single year, which almost always means a remodel or new construction.

We show year-by-year changes against the group's middle half, and 1, 3, 5 and 10-year average annual growth with your position among the group. A year where your value moved far more than the group's middle half is marked as unusual: that is a prompt to check for a remodel, a correction, or an appeal outcome, not a judgment.

Growth is never compared across counties or states, because different places assess on different bases.

Inspection cycle

Clark County physically inspects about one sixth of residential properties each year, by area, on a six-year cycle, and adjusts the rest from sales. Values often step in the inspection year. Comparing you with homes on the same cycle keeps that step from looking like a difference between you and your neighbors.

Sales ratio

Each year the assessor publishes the sales it used to set values, with prices adjusted to January 1. For homes in your assessor neighborhood that sold, we divide the county value by the adjusted sale price. A median ratio near 1.00 means county values track sale prices. The county's own standard, from the International Association of Assessing Officers, is a median between 0.90 and 1.10 and a spread (coefficient of dispersion) of 15 or less for similar houses, 20 or less for varied or rural areas. When your neighborhood has fewer than 20 sales in the latest year, we pool two years and say so.

Two models

Besides the direct comparison, two statistical models give a second opinion.

Sales-based estimate. We fit a model to the sales the county used for the last three revaluations: the logarithm of the adjusted price against living area, age, quality grade, lot size and assessor neighborhood, with a robust fit that limits the influence of odd sales. The model's error is measured by cross-validation (fitting on four fifths of the sales and testing on the fifth, five times) and is published with the estimate. We then estimate what your home would sell for and compare it with the county value.

Consistency check. The same kind of model fitted to the county's own current values. It asks whether your value is consistent with how the county valued every other home with your characteristics. Because the county uses similar models itself, this check is usually close; a large gap is a reason to look further.

What you can do

If the report raises a question, start with your property record on the county website and check the facts the county has on file (size, year built, quality, condition). In Clark County, a petition to the Board of Equalization must be received or postmarked within 60 days of the Notice of Value mailing date, or by July 1 of the assessment year (RCW 84.40.038). Filing is free, a Notice of Value is required, and evidence is due 21 business days before the hearing. Sales of similar homes are the strongest evidence; this report helps you find them.

Your tax bill

In Washington, each taxing district (the state school levy, your local school district, the county, your city or the county road fund, fire, library, port, parks and so on) sets a budget, which the law caps at 1% growth a year plus the value of new construction. The rate each district charges is simply that budget spread over all the taxable value in the district. So when values rise across the board, rates fall, and your bill does not rise with your value; it rises when your value grows faster than the district's total.

We show ten years of bills from the Treasurer's records and split each year's change into two parts: the value effect (how much the change in your taxable value would have moved the bill at last year's rate) and the rate effect (how much the change in your area's rate moved the bill at this year's value). Whatever is left is other charges: flat fees on the statement that are not based on value, such as stormwater or clean-water charges and weed-control assessments, and any exemption or correction.

The rate for your tax code area (the exact set of districts that bill you) is read from the county's annual levy report for the current year. For earlier years we use the median of bill ÷ taxable value across regularly taxed homes in the same area, which reproduces the published rate to a few cents per $1,000 and is available for every year we hold bills. Where this year's bill goes multiplies your taxable value by each district's rate from that report; the gap between the result and the bill is the flat charges.

Next year's estimate is this year's value at the current rate, with a range taken from how much the area's rate has moved year to year. The real rate is set in January.

Your share of the district compares the growth of your taxable value with the growth of all taxable value in your tax code area since the earliest year on record. New construction is included in the area's total, which is part of why a long-held home's share tends to shrink.

Relief

Washington's senior citizen and people with disabilities exemption lowers property tax for owners who are 61 or older (or retired because of a disability, or a qualifying veteran), live in the home as their principal residence, and have combined disposable income under the county's thresholds, which the Department of Revenue sets every few years. For Clark County in tax years 2024 to 2026 the tiers are $44,000, $53,000 and $62,000, with a deferral program up to $65,548. Participants pay none of the levies marked as exempt in the county's report, and lower tiers also exclude part of the home's value. We estimate the minimum saving from the exempt levies alone and show how many homes in your neighborhood use the program; we never show whether any particular neighbor does. A 2026 law change expands the program from 2027.

Dates that matter

Values are as of January 1. Most Notices of Value mail in June and the rest in September; only homes whose value changed receive one. An appeal must reach the Board of Equalization within 60 days of the notice's mailing date, or by July 1. Tax statements mail in mid-February; the first half is due April 30 and the second half October 31. The county physically inspects each area once every six years, and values often step in the inspection year. The "add to my calendar" button writes these dates into a standard calendar file that any calendar app can open.

Recent sales and the market range

The sales table lists recorded transfers in your assessor neighborhood from the last twelve months that the county has not flagged as invalid, with the county value as of the year of sale. The market range divides your county value by the middle half of the ratios of county value to sale price among the sales the assessor used for your neighborhood: if homes there typically sell for a little more than their county value, your county value implies a slightly higher sale price. It is a second opinion on the assessment, not a listing price.

Saved places

Addresses you look at are kept in your own browser, along with the value and bill you last saw, so a later visit can say what changed. Nothing is sent anywhere.

Neighborhood and county pages

Each assessor neighborhood has its own page: the middle of its values, how they moved year by year (homes that were built or rebuilt along the way left out), the sales ratio and spread against the standards, the sales the county used to set this year's values there, who bills the homes and at what rate, the share of homes corrected after the roll or using the exemption, permits issued in the last year, and every home in it. The county page puts the neighborhoods side by side and adds two fairness tests from the sales the assessor used: the median ratio by sale-price tier (if cheaper homes are valued at a higher share of their sale price than expensive ones, the bars fall from left to right), and the price-related differential and price-related bias, the two standard statistics for that question. All of it comes from the same tables as the reports, so a report and its neighborhood page never disagree.

Permits

Building permits come from the county's permitting map service, matched to parcels by the county's own parcel number. A permit on your parcel is usually the reason for a jump in value (an inspection after a remodel or an addition) and is evidence either way in an appeal. We keep the permit number, type, work type, status and date; the county's record also names the applicant or contractor, and we never store or show that.

Evidence packet

The printable packet arranges, in the order a Board of Equalization hearing reads it: the county's record of the home, the sales the county used in the neighborhood (market evidence as of January 1, closest in size first), the similar homes' values (equity evidence), and the deadline. It contains nothing that is not on the report.

Compare two homes and "if you buy at"

The compare page shows the same numbers for two homes side by side. The buyer's estimate applies the neighborhood's ratio of county value to sale price to a price you type, and the tax code area's rate to the result; the county does not reset a value to the sale price, it values all homes together each January 1, so this is the typical outcome, with the middle half of ratios as the range.

Sources and limits