For standard vehicles, not paying on time will leave you facing a penalty charge of £160. This will be reduced to half that amount should you pay within 14 days of getting the penalty. For HGVs and other large vehicles, drivers can be charged up to £1000 (again, this will be reduced by half if payment is made within 14 days of the penalty).
Other penalties may be given should drivers provide false information about their vehicle with regard to the ULEZ.