How do I know if I should appeal my property tax assessment?

You should appeal if your assessed value is higher than what you believe the property would sell for in the current market. The key evidence is recent comparable sales (homes similar to yours that sold nearby in the past 6-12 months). If you can find 3+ comparable sales at or below your estimated value, you have a strong case. General rule: if your assessed value is more than 5-10% above your estimated market value, the potential savings justify the time to file an appeal.

What percentage of property tax appeals succeed?

Nationally, approximately 40-50% of property tax appeals succeed in achieving some reduction. The average reduction for successful appeals is 10-15% of the assessed value. Success rates are higher when you have strong evidence — a professional appraisal, clear comparable sales, or errors in the assessment record (wrong square footage, incorrect bedroom count, etc.) can push success rates above 60-70% for well-prepared appeals.

Should I hire a tax appeal attorney or do it myself?

DIY appeals are almost always worth attempting — the only cost is 2-6 hours of your time, and the process is designed for homeowners without legal expertise. If your potential savings are under $1,000/year, DIY is the only financially sensible option. For larger savings ($2,000+/year), a flat-fee attorney ($200-$600) may be worth the peace of mind. Avoid contingency firms that take 25-50% of your first year's savings — this is expensive for what is often straightforward work you can do yourself.

What is the best evidence for a property tax appeal?

The strongest evidence, in order: (1) A professional appraisal from a licensed appraiser ($300-$600) showing value below your assessed value — assessors rarely dispute credentialed appraisals; (2) Recent comparable sales — 3-5 similar homes that sold near or below your assessed value in the past 6-12 months, obtained from Zillow, Redfin, or a real estate agent; (3) Errors in the assessment record — if the county has your square footage, bedroom count, or property features wrong, this is an automatic basis for reduction.

What happens to my property taxes in future years after a successful appeal?

A successful appeal reduces your assessed value, which becomes the new lower base for all future tax calculations until the next county-wide reassessment (typically every 3-5 years, though this varies by state). This means the savings compound over time — a $3,000 annual reduction saves $15,000 over five years, and as property values (and assessed values) appreciate, the percentage difference you locked in continues to produce savings. Always verify your assessment again at each reassessment cycle.

Property Tax Appeal Calculator

Find out if your property is overassessed, calculate potential savings, and decide whether to appeal — with state-specific deadlines, evidence checklists, and full ROI analysis.

Current Assessed Value

Your Estimated Fair Market Value

Property Tax Rate %

Your State

Current Annual Property Tax

$4,560

At assessed value of $380,000

Tax at Your Estimated Value

$3,840

At your FMV of $320,000

Potential Annual Savings

$720

If appeal succeeds at your estimated value

5-Year Cumulative Savings

$3,600

If appeal succeeds and basis holds for 5 years

Overassessment Amount

$60,000

15.8% above your estimated FMV

Appeal Recommendation

Worth appealing

15.8% overassessment — strong case

Key fact: Approximately 40-50% of property tax appeals succeed. The average reduction for successful appeals is 10-15%. DIY appeals cost nothing but your time. Even if you win a partial reduction, any decrease in your assessed value locks in lower taxes for future years until the next reassessment.

Advanced

Evidence Strength + Appeal Cost + Success Probability

How strong is your case and what will it cost?

Do you have recent comparable sales (comps)?

Do you have a professional appraisal?

Did you find errors in the assessment?

Evidence Score

40/100

Higher = stronger case

Adjusted Success Probability

55.0%

Based on your evidence strength

Recent comparable sales: Strong evidence (+40pts)

No professional appraisal: Consider getting one for $300-500

No errors found: Check square footage, bedroom count, and features

Best evidence: A professional appraisal from a licensed appraiser ($300-$600) is the strongest single piece of evidence — assessors and boards rarely dispute a credentialed appraisal. Comparable sales from the MLS (ask a real estate agent) show what similar properties actually sold for. Assessment errors (wrong square footage etc.) are automatic wins.

Pro

Appeal Timeline + Multi-Year Impact + ROI Analysis

State-specific deadlines, compound savings over time, and full ROI comparison

Filing Deadline — Texas

May 15 or 30 days after notice

File with Appraisal Review Board. Informal hearing available before formal protest.

Informal Review (Step 1)

Most counties offer an informal review with the assessor's office before formal proceedings. Success rate is high at this stage — often 30-60% of cases are resolved informally. Timeline: 2-8 weeks.

Formal Hearing (Step 2)

If informal review fails, you appear before the Board of Review/Equalization. Present your evidence (comps, appraisal, errors). Hearing typically scheduled 1-6 months after filing. Decision within 30-90 days.

Court Appeal (Step 3)

If the board denies your appeal, you can appeal to the state tax court or district court. This is rare for residential properties due to attorney costs — but available if your savings are substantial (typically $5,000+/year).

Missing the deadline = waiting another year. Property tax appeals are strictly time-limited. Most states give you 30-90 days from the assessment notice date. Calendar the deadline the day you receive your notice and start gathering comps immediately.

How to Use This Property Tax Appeal Calculator

This calculator answers the three key questions in any property tax appeal: Is my property overassessed? How much could I save? Is it worth the time and cost to appeal?

Quick Tier — The Core Numbers

Enter your current assessed value (from your assessment notice or county website), your estimated fair market value (what you believe the property would actually sell for based on recent comparable sales), and your tax rate. The calculator shows your potential annual and 5-year savings, the overassessment amount and percentage, and a recommendation on whether appealing is worth it.

Advanced Tier — Evidence and Cost Analysis

The Evidence Strength tab scores your case based on comparable sales, professional appraisals, and assessment errors — and adjusts your success probability accordingly. Appeal Cost breaks down DIY vs attorney vs contingency firm economics. Success Probability shows the national averages and your case-specific estimate.

Pro Tier — State Deadlines, Compound Savings, and ROI

The Appeal Timeline tab gives your state's specific filing deadline and appeal process overview. Multi-Year Impact projects compound savings as property values appreciate from the new lower base. ROI Analysis compares the return on each appeal method over 10 years.

The Core Formulas

Current Annual Tax = Assessed Value × Tax Rate ÷ 100
Tax at FMV = Your Estimated FMV × Tax Rate ÷ 100
Potential Annual Savings = Current Annual Tax − Tax at FMV
Overassessment % = (Assessed Value − Your FMV) ÷ Assessed Value × 100
5-Year Savings = Annual Savings × 5 (if basis holds)
Attorney ROI = (Annual Savings − Attorney Fee) ÷ Attorney Fee × 100

Note: successful appeals lock in a lower assessed value until the next county-wide reassessment. In most jurisdictions this is every 3-5 years, though some counties reassess annually.

Example: Homeowner Saves $2,400/Year in Illinois

Dave's Cook County Property Tax Appeal — Chicago Suburb

Dave's home was assessed at $420,000 after the county reassessment. He found three recent comparable sales in his neighborhood between $340,000 and $370,000 — suggesting the county overvalued his home by $60,000-$80,000.

Assessed Value	$420,000
Dave's Estimated FMV	$355,000
Illinois Tax Rate (Cook County)	~2.07%
Current Annual Tax	$8,694
Tax at Dave's FMV	$7,349
Potential Annual Savings	$1,345/year
5-Year Cumulative Savings	$6,725
Appeal Method	DIY (free)
Time Invested	~4 hours
Outcome	Reduced to $370,000 (partial win)
Actual Annual Savings	$1,040/year

Dave won a partial reduction and now saves over $1,000 annually with zero cost. The 4 hours he spent gathering comps and filing the appeal effectively paid him $260/hour in the first year alone, and the savings continue for years until the next reassessment.

The Property Tax Appeal Process

Most states follow a similar multi-step process:

Receive Assessment Notice: The county sends a notice of your new assessed value. This starts the appeal clock — don't lose this document.
Gather Evidence: Pull comparable sales from Zillow, Redfin, or ask a real estate agent for MLS data. Download your property record card from the county assessor's website and check for errors (wrong square footage, bedroom count, etc.).
Informal Review: Most counties allow you to call or visit the assessor's office to request an informal review before formal proceedings. Many appeals are resolved at this stage — often 30-60% succeed informally.
File Formal Appeal: If informal review fails, file a formal appeal with the Board of Review/Equalization before the deadline. Include all evidence. Fees are typically $0-$50.
Attend Hearing: Present your case to the board. Be factual and professional. Bring printed copies of all evidence. Hearings are typically 10-20 minutes for residential properties.
Receive Decision: The board issues a decision within 30-90 days. If denied, you can appeal to the state tax court (rarely worth it for residential unless savings are very large).

Frequently Asked Questions

Appeal if your assessed value is higher than what you believe the property would sell for today. Find 3+ comparable sales (similar homes that sold nearby in the past 6-12 months) using Zillow or Redfin. If those sales are at or below your estimated value, you have a solid case. General rule: if your assessed value is more than 5-10% above your estimated market value, the potential savings justify filing an appeal.

Nationally, approximately 40-50% of property tax appeals achieve some reduction. The average reduction is 10-15% of assessed value. Success rates are significantly higher with strong evidence — a professional appraisal, multiple comparable sales, or clear errors in the assessment record can push your odds above 60-70%. Even partial wins save real money over multiple years.

DIY appeals cost nothing but time (typically 2-6 hours) and are designed for homeowners without legal expertise. If your potential savings are under $1,000/year, DIY is the only economically sensible option. For savings over $2,000/year, a flat-fee attorney ($200-$600) can be worth it for professional presentation. Avoid contingency firms that take 25-50% of your first year's savings — you're paying a large premium for something you can likely do yourself.

In order of strength: (1) A professional appraisal from a licensed appraiser ($300-$600) — assessors rarely dispute credentialed appraisals; (2) Recent comparable sales — 3-5 similar nearby homes that sold at or below your assessed value in the past 6-12 months; (3) Assessment record errors — if the county has wrong square footage, bedroom count, or features, this is automatic grounds for reduction. Check your property record card on the county assessor's website.

A successful appeal reduces your assessed value, which becomes the new lower base for all future tax calculations until the next county-wide reassessment (typically every 3-5 years). As property values and assessed values appreciate over time, the savings compound from that lower starting point. A $2,000/year reduction saves $20,000 over 10 years before appreciation effects — and more with growth. Always appeal again at the next reassessment if values rise faster than the market.