Property Tax Protest ROI Calculator
Find out if your property tax protest is worth it — compare DIY vs hiring a firm, see probability-weighted expected savings, and get state-specific deadlines and evidence tips.
| Factor | DIY Protest | Hire a Firm |
|---|---|---|
| Cost | $0 | $188 |
| Success Rate | ~40% | ~65% |
| Avg Reduction | 8–10% | 10–15% |
| Time Required | 4–8 hours | 1–2 hours |
| Expected Net Value | $300 | $366 |
How to Use This Property Tax Protest ROI Calculator
Millions of properties are over-assessed every year — owners who protest get reductions. This calculator tells you whether your protest is worth the effort and whether to hire a firm or do it yourself.
Quick Calculator — Net Savings Analysis
Enter your assessed value (from your tax notice), your estimated fair market value (based on recent comparable sales), your effective tax rate, and the fee structure you would pay a protest firm. The calculator shows potential gross savings, firm cost, net first-year savings, and cumulative multi-year savings.
Advanced Tier — DIY vs Firm, Expected Value, and Cumulative ROI
The DIY vs Firm tab compares success rates, average reductions, time costs, and net expected value side-by-side. The Expected Value tab shows the probability-weighted outcome for each option. The Annual Protest ROI tab shows cumulative savings over multiple years of protesting.
Pro Tier — State Rules, Evidence, and Compound Savings
The State Rules tab gives specific deadlines and processes for Texas, California, Florida, New York, Illinois, Ohio, Georgia, Washington, New Jersey, and Pennsylvania. The Evidence Strategy tab covers what wins at a hearing. The Compound Savings tab shows how a lower base assessment compounds over years.
The Formulas Used
Potential Annual Savings = (Assessed Value − Fair Market Value) × Tax Rate / 100
Contingency Fee = Gross Savings × Fee Percentage
Net First-Year Savings = Gross Savings − Firm Fee
DIY Expected Value = 40% Success Rate × Gross Savings
Firm Expected Value = 65% Success Rate × Gross Savings − Firm Fee
Compound Savings Year N = (Baseline Tax × 1.03^N) − (Reduced Tax × 1.03^N)
Example: Property Tax Protest in Houston, TX
David protests his Harris County assessment
David's home in Houston is assessed at $420,000. He pulled three recent comps that averaged $375,000, suggesting a $45,000 over-assessment. His tax rate is 2.1% (Harris County). He is considering a firm at 25% contingency.
| Assessed Value | $420,000 |
| Fair Market Value (comps) | $375,000 |
| Over-Assessment | $45,000 (10.7%) |
| Tax Rate | 2.1% |
| Current Annual Tax | $8,820 |
| Potential Annual Savings | $945/year |
| Firm Fee (25% contingency) | $236 (Year 1 only) |
| Net First-Year Savings | $709 |
| 5-Year Cumulative Savings | $4,541 (net of Year 1 fee) |
| DIY Expected Value | $378 (40% of $945) |
| Firm Expected Value | $378 (65% × $945 − $236 × 65%) |
At 25% contingency, the firm and DIY have nearly identical expected value — but the firm does the work. David files the protest with his agent's comps. The informal hearing results in a $40,000 reduction, saving $840/year. Over 5 years that totals $4,410 in tax savings.
When to Protest Your Property Tax
- Clear over-assessment: If your assessed value is 5% or more above recent comparable sales, you have a strong case. A 10% over-assessment on a $400,000 home at a 1.5% tax rate is $600/year in excess taxes — well worth protesting.
- After a reassessment year: Mass appraisal errors are most common after counties conduct wide-scale reassessments. Pull your assessment notice and compare immediately to recent sale prices in your neighborhood.
- Market decline year: In years when home prices have dropped significantly, many assessments lag the market. Values assessed during a peak may be far above current prices.
- After purchasing: If you bought recently for less than the assessed value, your purchase price is the strongest single piece of evidence. Present the HUD-1 or closing disclosure at the hearing.
- Physical errors: If the county has incorrect data (wrong square footage, extra bathroom listed, wrong lot size), correcting those errors alone may generate a reduction without any market analysis.