Details of how tickets for the London 2012 Olympics and Paralympics can be resold have been confirmed.
People will be able to submit their tickets on the London Organising Committee (Locog) website between 6 January and 3 February.
These will then be made available online for other customers to buy and if sold, the seller will receive the full face value of the tickets.
Locog said this would help ensure venues were full during the Games.
Ticket holders, who bought tickets direct from Locog, will be able to select which tickets they want to resell using their account on the Locog website.
If the tickets remain unsold by 3 February they will be returned to the ticket holder's account. There will be a further opportunity to resell any unwanted tickets from spring 2012.
Those who bought tickets directly from overseas Authorised Ticket Resellers (ATR) and want to return them, should contact the ATR concerned.
Locog Chief Executive Officer Paul Deighton said: "We asked people to buy tickets more than a year out from the Games and, mindful of that, we promised that we would create this system for people whose circumstances may have changed to enable them to resell their tickets legally and safely.
"I'm convinced that most people will want to hold on to their tickets but we are pleased to offer this resale programme which will give those who wish to use it an opportunity to securely sell their tickets, or purchase more tickets and help us to achieve our aim of having full venues."
More than one million of the two million Paralympic tickets have already been sold with none remaining for track cycling and the marathon.
The remaining Paralympic tickets together with those for Olympic football are still on sale until 6 February, when seats will start to be allocated. Unsold tickets will go back on sale from the spring.
Ticket allocation for the Olympics earlier this year angered thousands of members of the public who were left empty-handed as the opening and closing ceremonies, athletics and cycling sold out.