These data are submitted by GP practices to NHS Digital as part of an annual collection as a 'reasonably accurate reflection of the contract'. GP Practices also have the facility to update their boundary on a live basis, to either reflect a contractual change, or improve the quality of their existing entry. Users of these data should be aware the data provided is an exact copy of what has been submitted, no onward data cleansing has been undertaken in making these data available, as a result some boundaries may be in need of further quality improvement. These data will be updated monthly, users will be able to identify which practices have amended their boundary in the supporting Excel file.