skills/ca-property-tax-appeal/references/tax-impact.md

# Tax-impact estimate

Use only the formula published by the relevant assessor, tax collector, finance department, or state authority.

## California

California's value-based secured real-property rate consists of the 1% general levy plus rates for qualifying voter-approved debt. The effective ad valorem rate therefore varies by tax-rate area. Obtain the subject property's exact percentage from its tax bill or an official County Auditor/Tax Collector source.

Estimate the value-based change as:

`estimated variable-tax change = (current taxable value - proposed taxable value) × exact ad valorem rate`

Do not apply the percentage to direct assessments, parcel taxes, Mello-Roos charges, fixed fees, delinquency charges, or other non-value-based items. List those separately as assumed unchanged unless the issuing agency says otherwise. A Proposition 8 reduction is temporary; later market-value restoration may exceed 2% in a year but may not exceed the factored base-year value absent another reassessable event.

## Common patterns

These examples are conceptual, not a substitute for local rules:

- Full-value system: taxable value may equal assessed value minus exemptions.
- Assessment-ratio system: taxable assessed value may equal market value multiplied by a statutory assessment ratio.
- Millage system: tax may equal taxable assessed value multiplied by total mills divided by 1,000.
- Rate-per-$100 system: tax may equal taxable assessed value divided by 100, multiplied by the rate.

Caps, classification ratios, exemptions, phase-ins, equalization factors, special districts, levies, and fixed charges can materially change the result.

## Calculation display

Always show:

- Current jurisdiction market-value basis.
- Proposed market-value basis.
- Assessment ratio or equalization factor, if applicable.
- Exemptions/caps used or excluded.
- Applicable variable rate and tax year.
- Current estimated tax, proposed estimated tax, and estimated difference.
- Source for every jurisdiction-specific input.

Use a formula block such as:

`estimated savings = (current taxable basis - proposed taxable basis) × applicable variable rate`

Label fixed charges as unaffected unless official guidance says otherwise. If the tax bill itself is available, reconcile the estimate to it and explain unexplained differences. Round sensibly and never present an estimate as guaranteed savings.

## Pre-filing cost-benefit screen

Before recommending that the user begin a paid formal appeal, verify the current county fee from the official Clerk/Assessment Appeals source. Include processing, filing, hearing, per-parcel, payment-card, and other unavoidable charges; state when each is due and whether it is refundable. Check for an official waiver, reduction, or free informal review. Never assume another county follows Santa Clara County's fee schedule.

When the exact ad valorem rate and a supportable proposed value are available, show:

`estimated first-year net benefit before other costs = estimated variable-tax reduction - unavoidable filing/payment fees`

`break-even assessed-value reduction = unavoidable filing/payment fees ÷ exact ad valorem rate`

Keep appraisal, representative, mailing, travel, time, and hearing costs separate. Include them only if the user supplies a reasonable amount or an official source establishes the charge. Do not multiply a temporary Proposition 8 reduction across future years as guaranteed savings.

Use one of these conclusions:

- `Appears financially favorable on current numbers`: the supported one-year variable-tax estimate exceeds verified unavoidable fees, evidence is at least moderate, and the deadline is open.
- `Close call`: the estimated one-year benefit is near the fee or material costs/evidence remain uncertain.
- `Appears financially unfavorable on current numbers`: verified unavoidable fees equal or exceed the supported one-year estimate. Explain that the user may still have nonfinancial reasons or a multi-year/base-value issue requiring professional advice.
- `Cannot tell yet`: assessed-value reduction, exact rate, fee, deadline, or evidence strength is missing.

This is a screening estimate, not a decision for the user. Show the arithmetic, uncertainty, possible value increase, nonrefundable-fee risk, time burden, and free or waiver path before asking whether they want to continue.