An appeal only makes sense if the tax savings outrun the cost of proving your case. This calculator converts an assessment reduction into annual and five-year savings, subtracts appraisal or attorney fees, and tells you the break-even month — so you file only when the math works.
Situation: The county values Mia’s home at $420,000. She finds four comparable sales at $355,000–$365,000 and files the evidence herself.
Rate / rule: Her effective rate is 1.8%. The reduction is $60,000. A DIY appeal costs nothing but her time.
Calculation: $60,000 × 1.8% = $1,080 saved per year. Cost $0. Break-even: immediate.
Situation: Sam’s assessment is $420,000 and he believes $390,000 is fair. He pays a $500 appraiser to support the number.
Rate / rule: Reduction $30,000 at a 1.8% rate yields $540 per year. The appraisal costs $500 up front.
Calculation: $30,000 × 1.8% = $540/year. Cost $500. Break-even ≈ 11 months.
Situation: Priya believes her $420,000 assessment should be $405,000 — only a $15,000 gap — but plans to sell in a year.
Rate / rule: Savings are $15,000 × 1.8% = $270/year. An attorney takes 35% of savings, leaving $175.50 per year.
Calculation: $270 gross − $94.50 contingency = $175.50 net per year, for one year of ownership.
Effective rate = total annual property tax ÷ assessed value. This is the millage expressed as a percent, and it is the number that turns an assessment cut into dollars.
Cost = $0 for DIY, the appraisal fee for a hired appraiser, or savings × contingency % for an attorney.
Break-even = cost ÷ annual savings, expressed in months.
Net savings = (annual savings − effective annual cost) × years you expect to own the home.
| State | Approx. effective rate | Appeal deadline pattern |
|---|---|---|
| Texas | 1.60 – 2.20% | May 15 or 30 days after notice |
| New Jersey | 2.10 – 2.50% | April 1 (county board) |
| Illinois | 1.90 – 2.30% | 30 days after township notice |
| California | 1.10 – 1.30% | Sep 15 – Nov 30 |
| Florida | 0.80 – 1.10% | 25 days after TRIM notice |
| Colorado | 0.50 – 0.70% | June 1 (varies by county) |
Assessment offices process enormous volumes, and errors are routine: stale square footage, a wrong condition grade, a comparable chosen from the wrong subdivision, or a homestead exemption not applied. In many jurisdictions a majority of formally filed appeals result in at least a partial reduction — yet the overwhelming majority of homeowners never file at all.
The reason is the upfront cost. An appraisal runs several hundred dollars and an attorney takes a slice of the savings, so the appeal only pencils out when the assessment gap is large relative to the rate. This calculator exists to answer that one question before you spend anything: does the reduction pay for the proof?
Two rules of thumb help. First, an appeal is rarely worth a professional fee on a gap below roughly 5% of value. Second, the longer you intend to own the home, the more a reduction compounds — most jurisdictions lock in the new assessment until the next reassessment cycle.
Boards weigh evidence, not opinions. A credible filing usually contains at least three of the following:
1. Comparable sales. Three to five settled sales within the last 12 months, in the same subdivision or a directly comparable one, adjusted for square footage, lot size, age and condition.
2. A licensed appraisal. Costly but the strongest single document, and many boards give it controlling weight.
3. A recent purchase price. If you bought the home recently in an arm’s-length sale, the price is powerful evidence — especially if you bought below the assessed value.
4. Concrete defects. Foundation problems, a failing roof, flood damage or an easement can all justify a lower grade. Photographs and contractor estimates carry weight.
5. A uniformity argument. In some states the remedy is proving your assessment ratio is higher than the median for your county, even if your market value estimate is correct.
| Route | Typical cost | Best when | Watch out for |
|---|---|---|---|
| DIY evidence pack | $0 | Gap is clear and comps are easy to find | Procedural deadlines; incomplete forms |
| Licensed appraiser | $350 – $700 | Value is genuinely contested | Fee is sunk even if you lose |
| Attorney, contingency | 25 – 40% of savings | Large gap, complex or commercial property | You surrender a third of the win |
| Attorney, flat fee | $500 – $2,500 | Hearing representation matters | Flat fee can exceed a small win |
The pattern is consistent: DIY wins on small and clear-cut reductions, an appraiser wins when the value is genuinely arguable, and an attorney only pays on a large gap where the contingency still leaves you ahead. A $15,000 reduction at a 1.8% rate generates $270 a year — a 35% contingency eats a third of that, which is why this calculator reports the break-even rather than just the savings.
⚠ Important Disclaimer: This is a planning estimate, not an appraisal or legal advice. Effective tax rates, appeal deadlines and the evidence a board will accept vary by state and county. Rates shown are illustrative. Confirm your local deadline and rules with the assessor’s office before filing.