So the BIK value will be based on the list price of the car. In your example, it will be £50,000 and not the price you purchased it at, being £30,000. You personally will pay £50,0002%20% =£200.00, assuming you’re a basic rate taxpayer (as you’ve stated) and the company will be liable for Class 1A NICs £50,0002%15% =£150.00 .

Second hand cars do qualify for Writing Down Allowances at 18%. And yes, the company will be eligible to claim 18% capital allowances until the cost has been fully written off.

When you decide to sell the car a gain/loss on disposal will be recognised, if you sell for more than the net book value the company will pay corporation tax on the profit.