Responses to Learning to Succeed, the white paper on 16 to 19-year-olds
The Association of Colleges warns that involving two different agencies in inspecting the same provision in the same classrooms will increase confusion.
It is also to mount a robust defence of college autonomy in the face of greater intervention through the new Learning and Skills Council.
The association says that it "regrets" ministers' decision not to establish a single inspectorate for post-16-year-old provision.
Ministers announced last summer that they would create "a new coherence and unity in the inspection process" by scrapping the college funding council's role in inspections.
Instead, the role of schools' inspectorate Ofsted would be extended to include 16 to 19-year-old provision in colleges and a separate body would be created to inspect post-19 education and training.
Although the white paper said that the inspection agencies would work together and form a "joint inspection where appropriate", college leaders are concerned that, as older and younger students take the same courses, in many cases both inspectorates will be responsible for the same provision.
The AoC said it will be "vital" that Ofsted and the new adult inspectorate "operate on the basis of a single, transparent model of inspection. That model should be based on clear and well-defined quality standards and provide consistent judgements ... It should include in particular a single inspection process for any institution carried out by a single inspection team of full-time professional inspectors directly employed by the inspection body."
In a recent update on the white paper, the Department for Education and Employment accepted that Ofsted and the new adult inspectorate "will need to agree a joint inspection programme and agree precise roles as part of that".
The AoC will also warn that planning under the new Learning and Skills Council, which will replace the Further Education Funding Council, must respect college autonomy.
The update stresses that local learning and skills councils will "negotiate the budgets and plans for individual further education colleges and work-based training providers, thereby exercising a key influence on which FE courses and training programmes will be funded and in what volume in their areas."
The AoC is also lobbying to ensure that funding for school sixth-forms, currently channelled through local authorities under a different methodology, is brought under the new regime as "an essential step towards the realisation of a coherent framework for post-16 planning and funding".