Car Tax Cost Calculator

Enter Vehicle Tax Inputs

This layout stays stacked by section, while the calculator fields adapt to 3 columns on large screens, 2 on medium, and 1 on mobile.

Example Data Table

Formula Used

1) Depreciated Value
Depreciated Value = Purchase Price × (1 − Depreciation Rate)^{Vehicle Age}
A 10% value floor is kept to avoid unrealistically low taxable values.

2) Selected Assessed Basis
The calculator uses the basis method you choose: purchase price, market value, depreciated value, lower comparison, higher comparison, or custom assessed value.

3) Prorated Taxable Value
Prorated Taxable Value = Selected Assessed Basis × (Months Taxed ÷ 12)

4) Base Tax
Base Tax = Prorated Taxable Value × Base Tax Rate

5) Emission Surcharge
Emission Surcharge = Max(0, CO₂ Emissions − CO₂ Threshold) × CO₂ Rate × (Months Taxed ÷ 12)

6) Engine Surcharge
Engine Surcharge = Ceiling[(Engine Size − Threshold) ÷ 100] × Rate per 100cc × (Months Taxed ÷ 12)

7) Luxury Tax
Luxury Tax = Max(0, Selected Basis − Luxury Threshold) × Luxury Rate × (Months Taxed ÷ 12)

8) Green Discount
Green Discount = Base Tax × Green Discount Rate

9) Regional Levy
Regional Levy = (Base Tax + Emission Surcharge + Engine Surcharge + Luxury Tax − Green Discount) × Regional Levy Rate

10) Final Payable Amount
Pre-Penalty Total = Base Tax + Emission Surcharge + Engine Surcharge + Luxury Tax + Regional Levy + Fixed Fees − Green Discount
Late Penalty = Pre-Penalty Total × Late Penalty Rate × Late Months
Net Tax Due = Max(0, Pre-Penalty Total + Late Penalty − Rebate Amount − Tax Credit)

How to Use This Calculator

Enter the vehicle purchase price, current market value, and age. These values establish the possible tax basis for the calculation.

Select the tax basis method that best matches your local rules. Use custom assessed value only when you already know the authority’s assessed amount.

Enter months taxed to support full-year or partial-year ownership. This prorates variable tax components automatically.

Fill in emissions, engine size, thresholds, and applicable surcharge rates. These capture environmental and displacement-based tax adjustments.

Add any luxury threshold, regional levy, and fixed fees. Then include late months, penalty rate, rebate amount, and tax credit.

Press the calculate button. The calculator shows a full result summary above the form, breaks down every tax component, and draws a Plotly chart.

Use the CSV button to export the breakdown into spreadsheet-friendly format, or use the PDF button to save a quick reporting copy.

Frequently Asked Questions