The Highways Agency initiated discussions with Severn River Crossing plc about increasing the toll levels on 18 October 2006.
The formula for determining the annual increase is set out in the Severn Bridges Act 1992 and in the concession agreement between the Government and Severn River Crossings plc.
New toll levels are introduced on 1 January and are confirmed each year by a Statutory Instrument made in December which authorises Severn River Crossing plc to adjust tolls to the revised levels.