How is zakat calculated for cars designated for sale and rental, as well as personal cars that fluctuate between being used and being offered for sale, given that zakat has not been paid since 2009, and how can it be paid for the past years?

Cars that you bought with the intention of trading them are considered trade goods, and zakat is due on them by assessing their value each year. Other assets you own should be added to this assessment when the hawl (one lunar year) passes. You should then pay a quarter of a tenth (2.5%) for each year if the total amount reaches the nisab. As for cars designated solely for rental, without the intention of trading them, zakat is due on their income if a hawl passes over it and it reaches the nisab (equivalent to 85 grams of gold or 595 grams of silver). Zakat is not due on a car if it was not bought with the intention of trade, even if it is sold later. Bank installments are deducted from the value of cars subject to zakat, and zakat is paid on the remainder if it reaches the nisab. Delaying the payment of zakat without a valid excuse is a sin that requires repentance.