Severn Bridge tolls could be charged until 2027.
That is the cut off date the British Government has to continue charging even when the concession to Bridge builders ends in 2018.
The additional nine-years of possible tolls has been unearthed by Plaid Cymru during discussions on the annual price rises, which took affect again last week.
The Government has remained silent on its plans and the Welsh Government is hopeful it will take over responsibility for the old and new Severn Crossings in 2018 and be able to slash the prices.
The tolls are seen as a drain on the Welsh economy and deterrent to investment west of the bridges.