MOT testing is a requirement for all vehicles over three years old, with the purpose of making sure that your car meets the minimum safety requirements. Without a valid MOT, your car insurance and road tax become invalidated and your car may not be road worthy. Therefore, it is important that you make sure your MOT certificate is in date and you book your next MOT before your current certificate expires. You can do this up to one month before the end of your current MOT certificate.