Luxury car tax (LCT) is a tax on cars with a GST-inclusive value above the LCT threshold. Liquor Consumption Tax (LCT) is a 10 per cent tax on the total selling price of beer, wine and spirits. LCT is charged in addition to the Goods and Services Tax (GST), but it is not payable on the full price of the vehicle. Formula to apply luxury car tax (LCT) to the value of a luxury car above the LCT threshold, less GST. Son of Holdback & Luxury Car Tax (LCT). The LCT in built into the invoice price charged by the dealer and can add a significant amount to the ultimate price you pay for your car.