Documenting a factual error in your property record
The easiest win available, and it needs evidence rather than argument.
The strongest appeal is not an argument about value. It is a demonstration that the county's record does not describe your property. Either the file matches the building or it does not, and there is very little room for disagreement.
The errors that occur
| Error | Proof that works |
|---|---|
| Floor area too large | Survey, architect's plans, purchase appraisal, or your own measured sketch |
| Basement recorded as finished | Dated photographs; a contractor's statement |
| Garage or outbuilding no longer exists | Demolition permit; photographs; aerial imagery |
| Wrong number of bedrooms or bathrooms | Plans, photographs, listing history |
| Lot size wrong | Plat of survey, deed |
| Wrong class code | The county's own class definitions, against what the property is |
| Building damaged or destroyed | Insurance claim, fire report, photographs |
How to document it so it cannot be argued with
State the two figures side by side. "The record shows 2,412 square feet. The survey attached shows 1,908 square feet." No adjectives, no complaint, just the discrepancy.
Attach the source, not a description of it. The survey itself, the permit itself, the photograph itself.
Date everything. A photograph without a date proves the condition at an unknown time.
Show the consequence. "At the recorded rate of $15.96 per square foot, the 504 square feet the record contains in error account for $8,044 of assessed value." Do the arithmetic for them.
Measuring a house properly
If you are measuring yourself, use the same convention the assessor does — usually gross exterior dimensions of finished, above-grade living area. That normally excludes an unfinished basement, a garage, and open porches, though counties differ.
Sketch each floor, mark the dimensions, calculate each rectangle, and total them. A clear hand-drawn sketch with dimensions is genuinely acceptable and frequently persuasive. Ask the office which convention they use before you start; a measurement taken on a different basis proves nothing.
Try the phone first
A factual error often does not need an appeal at all. Many offices will correct a demonstrable error directly, sometimes within days, and some will do it for prior years through a certificate of error — which produces a refund rather than a future reduction.
Call, describe it as a factual matter rather than a complaint about value, and ask what they need. If the deadline is close, file the appeal first and talk afterwards; an appeal can be withdrawn, a missed deadline cannot.
Fix the record, not just the year
This is the step people miss. Winning an appeal changes this year's number. If the underlying record is still wrong, the next reassessment rebuilds from the same bad data and regenerates the same error.
Ask explicitly for the record to be corrected, not just the assessment reduced. It is the difference between a one-cycle win and a permanent one.