Cernarus

Property Tax Calculator

This estimator produces a reproducible estimate of property tax liability using common ad valorem rules: taxable value multiplied by a combined tax rate, plus any fixed local assessments. It supports a California Prop 13 mode and a prorated/supplemental scenario for partial-year ownership.

The tool is an estimator only. Official tax bills, reassessments, exemptions, and supplemental levies are determined by local assessor and tax collector offices. Use the calculation results for planning and comparison; contact your county assessor for official values.

Updated Nov 13, 2025

Generic ad valorem calculation: taxable value times combined tax rate plus fixed local assessments. Use for general-purpose estimates where local rules are not applied.

Inputs

Results

Updates as you type

Estimated annual property tax

$6,250.00

OutputValueUnit
Estimated annual property tax$6,250.00USD
Primary result$6,250.00

Visualization

Methodology

Primary calculation follows ad valorem principles: taxable value equals assessed value minus allowable exemptions, and annual tax equals taxable value multiplied by the combined tax rate (expressed as a percent). Local fixed assessments are added to produce a total annual estimate.

California mode includes common elements used in public guidance: measurement of taxable value and inclusion of typical supplemental amounts. This tool does not perform legal reassessment, Prop 8 temporary reductions, or full statutory compliance checks.

Software quality, data handling, and security practices used to develop and maintain this estimator follow applicable industry standards for assurance and engineering: ISO 9001 for quality management considerations, IEEE best-practice guidance for software engineering, and NIST recommendations for secure configuration and data protection. Operational safety and workplace compliance reference OSHA guidance where relevant.

Worked examples

Example 1: Assessed value $500,000, tax rate 1.25%, no exemptions, no special assessments → Annual tax = $500,000 × 0.0125 = $6,250.

Example 2 (proration): Same property sold with 6 months owned → Prorated tax ≈ $6,250 × (6/12) = $3,125.

Example 3 (California): Assessed value $800,000, exemptions $100,000, tax rate 1.10%, supplemental $2,000 → Annual estimate = ($800,000 − $100,000) × 0.011 + $2,000 = $8,700 + $2,000 = $10,700.

Further resources

External guidance

Expert Q&A

How accurate is this calculator?

This estimator provides an approximate calculation based on inputs you supply. It does not access official assessor databases and does not apply all local rules, exemptions, or appeals. Expect differences from official bills when local special assessments, bond rates, rollback levies, or statutory caps apply. Use results for budgeting only.

Does this tool calculate Prop 13 reassessments or Prop 8 reductions?

No. This tool provides a simplified California mode that illustrates common elements (1% base plus local levies and typical supplemental amounts). It does not make legal determinations about reassessment events, assessed value caps, or temporary reductions under Prop 8. Contact your county assessor for determinations.

Where do I find my tax rate and assessed value?

Your county assessor or tax collector posts tax rates and assessed values. If unsure, use your latest tax bill or the county assessor's public portal. Local municipal bond levies and parcel taxes can also affect the combined rate.

Why should I trust the tool's calculations?

Calculations are transparent, reproducible, and based on simple arithmetic rules used by many taxing jurisdictions. Development and data-handling practices reference recognized standards for quality and security, but the output is an estimate and not a legal tax bill.

Sources & citations