The average level of per-student funding for 16 to 19-year-olds is £1,000 less than at key stage 4 – and almost £4,000 less than at university.
The disparity has caused six professional associations to write a joint letter to education secretary Michael Gove demanding action.
In 2011/12, the median income per-pupil aged 14 to 16 was £5,620, while the average university fee was £8,414 per student.
However, the average funding for a 16 to 19-year-old in school or college was £4,645 in 2011/12, with fears it will fall as low as £4,400 by 2015.
The signatories say the shortfall and resulting pressure on resources mean that schools and colleges are reducing tutorial support for students, cutting additional activities as well as pastoral and learning support, reducing teaching time and increasing class sizes.
The letter calls for Mr Gove to fight for the situation to be addressed in the next Comprehensive Spending Review. The signatories also point out that colleges are required to pay VAT meaning they face even further pressure on funds.
The letter has been written by the Association of School and College Leaders, the Sixth Form Colleges Association, the Association of Colleges, Freedom and Autonomy for Schools – National Association, the Independent Academies Association, and the Principals Professional Council.
They argue that the funding problems are also leading to the withdrawal of less popular courses such as languages, further maths and economics.
The letter includes a four-page paper presenting evidence of the funding dip and its consequences. As part of this, a study of school and college leaders found that
80 per cent believe they will have to reduce the choice of courses on offer, while two-thirds say they will have to reduce post-16 enrichment activities.
The letter states: “We are concerned that the 16 to 19 funding dip could stymie the best endeavours of schools and colleges to cultivate the potential talents of young people. The 16 to 19 funding dip has appeared as an unwelcome anomaly. An anomaly that we believe should be removed.
“It is important that education for this age group is appropriately funded, particularly as the age at which young people are required to continue in education or training increases to 17 this year and 18 in 2015.”
The letter comes as a separate survey found that 90 per cent of teachers in 6th form colleges believe funding cuts are hitting students’ education.
The National Union of Teachers’ poll of 500 professionals expressed concerns about the effects of cuts to staffing and courses, as well as the axed Education Maintenance Allowance and problems of larger class sizes.
Three-quarters of the teachers said the range of subjects being offered at 16 to 19 would narrow as a result in the next two years.