Property tax appeal ROI calculator

Inputs

Current assessed value	$450,000
Your fair market estimate	$400,000
Effective property tax rate	1.2%
Years until next reassessment	3
Appeal cost (filing + appraisal)	$500

Supporting metrics

Annual tax savings	$600
Total savings over years	$1,800
ROI	260%

About this calculator

When to appeal — math, not vibes

Most homeowners assume a property tax appeal is a long shot. The data says otherwise: 30-50% of appeals win at least partial reductions in counties that allow comp-based appeals (most US counties).

The breakeven

annual savings = assessed reduction × tax rate
total savings = annual × years until next reassessment
ROI = (total savings − appeal cost) ÷ appeal cost

A $50k overassessment in a 1.2% county saves $600/yr × 3 years = $1,800 against ~$500 appeal cost. 260% ROI on a 10-hour project.

When NOT to appeal

Your home actually IS worth the assessment (check 3-month sold comps)
You're refinancing soon (lower assessment can spook some lenders)
Your county uses sales-price-as-assessment (CA Prop 13) — appeal won't help
You bought recently above the assessment — your purchase is the comp

FAQ

How do I find comps for the appeal?

Last 6-12 months of arms-length sales within 0.5 miles, similar bed/bath/sqft. Free sources: Zillow / Redfin sold list. Paid: county MLS access via a Realtor friend. Three strong comps within 5% of your estimate is plenty for most appeals.

Will I need an appraisal?

For appeals over a $25k reduction, yes — most boards expect a professional appraisal ($350-600). Below $25k reduction, comps + photos of your home's condition deficiencies are typically enough.

What's the worst case?

Some counties allow the assessor to RAISE your assessment if your appeal evidence backfires. Rare but real (Cook County IL, NY). Always check local rules: the answer is usually no, but verify before you file.