The aircraft will be hired by commercial airlines and quickly painted in their flagship colours for use.
If the RAF need them back during a time of crisis they will be painted back again.
It is the first time that aircraft not needed by the military will be leased out to commercial airlines.
The idea is part of new measures to save the Ministry of Defence money.
Fourteen Airbus A330s are being bought by the company AirTanker and these will be leased by the Ministry of Defence.
The deal will cost the taxpayer an estimated £13bn over almost 30 years and is the world's biggest defence Private Finance Initiative.
When the aircraft are not being used by the RAF, AirTanker will make them available for commercial hire.
"They (the RAF) pay us for two things," said Phill Blundell AirTanker's chief executive.
"They pay us to make aircraft available to them, and then they pay when they fly.
"If they don't want the aircraft, or they don't want to fly them, then we take those aircraft and earn some money out of them."
Eleven years in negotiation, the deal helps the air force solve problems with its transport and airborne tanker fleet.
The 14 planes will replace elderly second-hand TriStar and VC10 airliners which have caused frustrating delays for troops waiting to fly home from duty in Afghanistan.
"These aircraft are like vintage cars," said Group Captain Peter Dixon. "They require a lot of care and attention to keep them going.
"The new fleet will be provided on time, hopefully exactly to cost and that's a rare thing these days, certainly for military procurement."
From 2011, five A330s will be permanently available to the air force, with another four on standby and the remaining five hired out to commercial airlines.
AirTanker supplies the aircraft and all their support services. The RAF will only provide the crews to fly them and the fuel.
The first planes will spend 12 months in Spain being converted to tankers.
He who laughs last obviously has'nt heard the bad news.