University candidates will be matched with available places in an early version of clearing to be launched next week.
Applicants who do not yet hold any offers will be allowed to approach universities that have unfilled places under the scheme being unveiled by the Universities and Colleges Admissions Service.
Candidates who have made unsuccessful applications and those who have rejected offers because they have changed their minds about an institution or subject will also be able to use the scheme, called Ucas Extra. Up to 45,000 hopefuls are expected to use the service between now and July.
A spokeswoman said: "Extra is optional and designed to encourage applicants to continue researching and choosing courses."
Ucas is writing to applicants who are eligible for Extra and will continue to contact other candidates as they become eligible. The courses available through Extra will be listed on the Ucas website and advertised once a month in newspapers from March 18.
On the basis of this information, applicants will choose where to apply.
Ucas will give universities and colleges ten days to respond. If no offer is made, the candidate can try again for a different course or institution.
Once an offer is accepted, the candidate cannot apply for further places.
Dai Hall, head of admissions at Greenwich University, said: "In the past, if someone was rejected by all six universities or they rejected offers because they changed their mind, they spent months in limbo. Now people can get on with applying. It's a very good service that Ucas has introduced."
The university - which normally takes 16 per cent of its students through clearing - expects up to 8,000 approaches to come through Extra.