Can I appeal my property taxes if the square footage is wrong?

Usually, yes. A factual error on the assessor's property record card, such as the wrong square footage, is a common basis for asking for a review. Start by contacting the assessor's office for an informal review with your evidence. If that doesn't resolve it, file a formal appeal with the local board by the deadline printed on your assessment notice. The process and its names vary by state and county.

How do I find the square footage the county has for my house?

Look up your property record card, usually on the county assessor's or property appraiser's website by address or parcel number, or ask the assessor's office for a copy. It typically shows the living area and often a sketch with the exterior dimensions the county used, which makes it easier to see where an error came from.

What evidence do I need to appeal wrong square footage?

A measured floor plan with dimensions for each level, photos that support it (exterior walls, low ceilings, unfinished or unheated spaces), a short statement of how you measured, such as following ANSI Z765-2021, and a table comparing your figures with the record card. A recent appraisal that measured the house also helps.

Will correcting the square footage lower my property taxes?

Not necessarily, and not by a predictable amount. Square footage is one input to the assessor's valuation; how a correction changes the assessed value depends on your jurisdiction's methods, and the tax also depends on local rates and exemptions. A correction can also raise the assessment if your home turns out to be larger than the record. Ask your assessor how a size change is applied.

What is the deadline to appeal a property tax assessment?

It varies by state and county. The deadline is usually printed on your assessment notice, along with where and how to file. A late appeal may not be accepted, so check the notice as soon as it arrives and ask the assessor's office if it isn't clear.

Do I need an appraiser for a property tax appeal on square footage?

Not always. For a factual error like square footage, a careful measurement with a floor plan, photos and a statement of method is often enough to start an informal review. A professional measurement or appraisal may help if the house is complex, the gap is disputed, or the appeal goes to a formal hearing. Your assessor's office can tell you what evidence the board accepts.

Guide

Property Tax Appeal for Wrong Square Footage

If the county has your square footage wrong, you may be overpaying. How to measure, document and appeal an assessment based on the wrong size.

Updated October 12, 2026 · FloorFigures

Short answer

If the assessor's record shows more square footage than your home has, get your property record card, measure the house, and ask the assessor for an informal review with a measured floor plan, photos and a statement of how you measured (for example, ANSI Z765-2021). If that doesn't fix it, file a formal appeal with the local board by the deadline on your assessment notice. A correction isn't a guaranteed tax cut: the assessor decides how size affects value.

Your property tax starts from an assessed value, and the assessor's record of your home (its size, age, rooms and features) feeds that value. If the record lists the wrong square footage, the value may rest on a house you don't have. Wrong square footage is a factual error, which makes it one of the more straightforward things to raise with an assessor. Here's the general process and how to document it.

The appeal process, step by step

1
Read your assessment notice
Find the assessed value, the deadline to appeal and where to file. Deadlines vary by state and county; put yours on the calendar first.
2
Get your property record card
Look it up on the assessor's website or ask for a copy. Check the square footage and every other fact on it.
3
Measure the house
Measure the outside walls level by level, or measure a floor plan with a checked scale. See how to measure a house.
4
Ask for an informal review
Contact the assessor's office, explain the error and send your evidence. A factual error may be corrected here, without a formal appeal.
5
File a formal appeal if needed
If the informal review doesn't resolve it, file with the local appeals board by the deadline on your notice, using the form and format it asks for.

What to check on the property record card

Record cards differ by county, but they typically include the facts below. Check each one, not just the total.

Field	What to look for
Living area	The total, and how it splits by level, if shown
Sketch and dimensions	Cards often include a sketch of the outline; compare each dimension with your measurement
Basement	Whether finished basement space is counted as living area, listed separately or missing
Porches, decks and sunrooms	Whether a porch that isn't usable year-round has been counted as living area
Garage	Whether it's been counted as living area, or a garage conversion is missing
Additions	Whether an addition is recorded once, at the right size
Rooms and baths	Bedroom and bathroom counts, which can affect value too

Compare like with like

The county may not measure the way an appraiser does. Assessors use their own local methods, and some count finished below-grade space as living area while others list it separately. Before you claim an error, make sure your figure and the county's describe the same thing. Ask the assessor's office how it measures if the card doesn't say.

If you want a standard to point to, use ANSI Z765-2021, the national standard appraisers follow: each level measured to the exterior finished surface of the outside walls, garages never counted as finished area, below-grade levels reported separately, and a 7 ft minimum ceiling. It's not the law for tax purposes, but it's a published, checkable method.

What evidence helps?

Evidence	Why it helps
A measured floor plan	Shows every dimension and how the total was reached, level by level
Photos	Show what the numbers can't: an unheated porch, an unfinished room, a low ceiling, the exterior walls
A statement of method	Says how you measured (for example, ANSI Z765-2021, to the exterior finished surface, to the nearest inch)
A comparison table	Puts your figures next to the record card's, line by line
A recent appraisal	An independent measurement, if one was done for a purchase or refinance
Plans or permits	Show what was built and when, especially for additions

If you measured from plans rather than the house itself, say so. ANSI Z765 requires a declaration in that case: "Finished square footage calculations for this house were made based on plan dimensions only and may vary from the finished square footage of the house as built." Being upfront about your method makes your figure easier to accept.

How to present the calculation

Keep it short and line by line, so a reviewer can check every number. In this example the record card lists 2,452 sq ft of living area; measuring shows the difference is a three-season porch that was counted as living space.

Area	Your measurement	Area	Record card
Main level	41'0" × 32'0"	1,312 sq ft
Upper level	32'0" × 27'6"	880 sq ft
Living area		2,192 sq ft	2,452 sq ft
Three-season porch (not heated, not living area)	20'0" × 13'0"	260 sq ft	Included in living area
Difference			260 sq ft (10.6% of 2,452)

Then one or two sentences of method, for example:

Measured on site to the exterior finished surface of the outside walls, to the nearest inch, following ANSI Z765-2021. The rear porch is enclosed with screens and windows but is not heated or suitable for year-round use, so it is not finished area. Photos 1–4 attached.

Point to the error and the evidence, and leave the valuation to the assessor. Stay factual: the size is wrong, here's the measurement, here's how it was done.

Will it lower your taxes?

There's no way to promise a saving. Square footage is one input to the assessed value, alongside location, age, condition and features, and each jurisdiction applies it differently. The tax itself also depends on local rates and exemptions. What a correction does is make the record match your home. Ask your assessor how a change in size is reflected in the value, and for a complex or high-value case, consider a professional who handles assessment appeals.

Preparing the floor plan with FloorFigures

FloorFigures is a free tool that measures a floor plan in your browser, from a PDF, an image, or a sketch of your own field measurements. It applies ANSI Z765-style rules (garage, porch and below-grade areas kept apart from living area) and exports a PDF report with the plan and measured areas, the scale statement and check, an area summary, a copyable ANSI statement and a comparison with the county figure. That's most of the evidence package in one document. Nothing is uploaded. To check the arithmetic of a gap, use the square footage discrepancy calculator.

Questions

Can I appeal my property taxes if the square footage is wrong?: Usually, yes. A factual error on the assessor's property record card, such as the wrong square footage, is a common basis for asking for a review. Start by contacting the assessor's office for an informal review with your evidence. If that doesn't resolve it, file a formal appeal with the local board by the deadline printed on your assessment notice. The process and its names vary by state and county.
How do I find the square footage the county has for my house?: Look up your property record card, usually on the county assessor's or property appraiser's website by address or parcel number, or ask the assessor's office for a copy. It typically shows the living area and often a sketch with the exterior dimensions the county used, which makes it easier to see where an error came from.
What evidence do I need to appeal wrong square footage?: A measured floor plan with dimensions for each level, photos that support it (exterior walls, low ceilings, unfinished or unheated spaces), a short statement of how you measured, such as following ANSI Z765-2021, and a table comparing your figures with the record card. A recent appraisal that measured the house also helps.
Will correcting the square footage lower my property taxes?: Not necessarily, and not by a predictable amount. Square footage is one input to the assessor's valuation; how a correction changes the assessed value depends on your jurisdiction's methods, and the tax also depends on local rates and exemptions. A correction can also raise the assessment if your home turns out to be larger than the record. Ask your assessor how a size change is applied.
What is the deadline to appeal a property tax assessment?: It varies by state and county. The deadline is usually printed on your assessment notice, along with where and how to file. A late appeal may not be accepted, so check the notice as soon as it arrives and ask the assessor's office if it isn't clear.
Do I need an appraiser for a property tax appeal on square footage?: Not always. For a factual error like square footage, a careful measurement with a floor plan, photos and a statement of method is often enough to start an informal review. A professional measurement or appraisal may help if the house is complex, the gap is disputed, or the appeal goes to a formal hearing. Your assessor's office can tell you what evidence the board accepts.