Abstract: A method of monitoring car parking obtains entry data containing at least one entry record, and exit data containing at least one exit record, wherein each entry/exit record contains a vehicle registration number and an entry/exit time. Entry and exit records that have the same vehicle registration number are matched to produce at least one parking record, wherein each parking record contains a vehicle registration number and an indication of a time stayed. Payment data containing at least one payment record is obtained, wherein each payment record contains a vehicle registration number and an indication of a period of time corresponding to a fee paid. For each parking record, either a payment record is identified that has the same vehicle registration number. It is determined whether the indication of time stayed exceeds the period of time in the identified payment record, or if there is no matching payment record identified.