Can I appeal because my neighbor's assessment is lower?

A lower assessment on a comparable neighbor can be a legitimate basis to appeal, because most states require properties to be assessed uniformly — similar homes should carry similar values relative to the market. This is sometimes a stronger argument than "my home is worth less than its assessment," especially in markets where prices are rising.

The principle: uniformity / equity. Assessment systems are built on the idea that comparable properties are valued consistently. The IAAO Standard on Mass Appraisal of Real Property treats uniformity as a core measure of assessment quality. If two near-identical homes in the same neighborhood carry very different assessed values, the higher one may be out of line.

How states frame it:

• Texas allows an "equal and uniform" challenge: under Tex. Tax Code §41.43(b)(3), an assessment is excessive if it exceeds the median appraised value of a reasonable number of comparable properties appropriately adjusted. The Texas Comptroller lists "unequal appraisal" as a protest ground.
• Cook County, IL explicitly accepts a "lack of uniformity" appeal — the Cook County Assessor states uniformity "requires that two or more properties in a neighborhood that are similar in size, type of construction, age and style have similar assessed values," and lets you attach up to six comparable PINs.

The right comparison is assessment-to-assessment, not just one neighbor. One lower neighbor isn't enough; boards look at a set of comparable properties. Pull the assessed values of several similar nearby homes (same size, age, style, condition) from the public record and show your assessment sits above the group. In fractional-assessment states, compare assessed values or ratios consistently — don't mix raw assessed values with sale prices.

Caveats. Genuine differences (a renovation, a larger lot, a finished basement) explain a higher value, so pick truly comparable homes. And a neighbor's lower value may simply reflect a homestead/senior cap that doesn't apply to you. Verify each comparable is actually similar before relying on it.