The postcode premium approach to widening access is inefficient and unjust, according to two Northern Irish researchers.
Bob Osborne, from Ulster University, and Ian Shuttleworth, from Queen's University Belfast, have found that in some cases supposedly poor postcode areas produce the same proportion of relatively well-off university applicants as more affluent areas.
If so, universities using a postcode system could recruit a middle-class student from a poor postcode area and receive extra cash for that student.
Northern Ireland is the only part of the UK that does not use the postcode premium, which gives institutions extra funding for students from areas of low participation. The premium given to Northern Ireland's universities is instead based on means testing.
Professor Osborne and Dr Shuttleworth, who generated results by transposing the English and Welsh postcoding system onto Northern Ireland, said that focusing on areas rather than individuals had major flaws in terms of correctly identifying students from deprived backgrounds.
In an article to be published in the journal Higher Education Management and Policy , they report that 15 per cent of higher education applicants came from sub-professional social class II in both the highest and lowest participation - theoretically, the richest and poorest - postcode areas.
The researchers also found a substantial overlap between postcode areas when it came to applicants from the skilled-worker grade, social class III.
"This indicates that there is no guarantee that the social background of higher education applications differs according to their residential location and its social context," the paper says.
It warns that a geographical policy that aims to encourage applicants from deprived areas could, in some cases, benefit the same types of people as live in more affluent areas.
The researchers argue that the scheme would be useful if it could be shown that the widening-participation benefits outweighed its major weaknesses.
But they point to the performance indicators published by the Higher Education Funding Council for England, which show no significant improvement in widening access under the postcode system.
The English, Scottish and Welsh higher education funding councils last year paid out £44.5 million through the postcode premium.