Careers advice has been reduced in more than eight out of 10 schools in England in the past year, research suggests.
A survey of professional careers advisers working in 1,500 secondary schools reveals "dramatic reductions" in the amount of professional careers guidance on offer.
Schools took over the duty to secure independent careers guidance for their pupils from September 2012.
The government says schools should decide what was right for them.
The Careers England research was undertaken because of widespread fears about the impact of the change brought about by the Education Act 2011 in England. Previously local authorities provided careers services to schools mainly through local Connexions Service.
'Schools let down'
The trade organisation asked a company to survey all 21 of its full members online in October about the careers services they have been providing to schools over the academic years 2011-12 and 2012-13
The results showed the level of careers advice has been maintained in only 16.5% of the 1,568 schools covered in the survey.
Careers England said this meant that 83.5% of schools had reduced provision.
Chairman of the Careers England board Steve Stewart said if the survey results were replicated across all schools it would translate to cuts in 3,300 schools.
He said: "Schools have been let down by the Department for Education, poorly prepared for the transition to their new role.
"And to expect more and better careers guidance for students, when schools have not a penny more for the new duty is not delegation of the duty to schools - it is abdication of by the Department for Education.
"This survey tells us bluntly that too much has been left to chance."
'Tight labour market'
He said that many schools were struggling with what the new duty meant and said there should be "a test of sufficiency in how the duty is fulfilled".
His colleague Careers England director Paul Chubb said: "The worst thing about this is the fact that we told government what would happen.
"When they tried this in the Netherlands and New Zealand there was a reduction in the available labour market of informed independent careers advice. Our survey confirms this has happened in England."
He said the cuts were happening against a backdrop of a "very tight labour market" and as vocational routes into employment are being undermined".
The report also suggested some schools are unable to afford to provide the same levels of careers guidance.
It gave the example of a school reducing the 65 days of careers guidance support from its local Connexions Service in 2011-12 to 16 days of bought-in support in 2012-13.
The report was published as the latest figures showed more than a million young people aged 16 to 24 were not in education, employment or training in September.
A Department for Education spokesperson said: "Young people need good quality careers advice - but the sad fact is that too much provision has been poor quality and patchy.
"We have introduced a new legal duty on schools to secure independent and impartial careers guidance for their pupils.
"They know their students best, so it is right that they should decide what provision is right for them and that they have complete control over their budgets to buy in the support they need."
Shadow education minister Karen Buck said the research confirmed what we have been hearing from schools and colleges across the country.
"Many are struggling to maintain a quality offer of careers advice and guidance because of the changes brought in by this government, with reduced financial support from September.
"Students and employers will be the losers as young people face being left with reduced ability to choose the best options for qualifications, training and work."
The findings of the survey have been submitted to the Commons Education Select Committee which is holding an inquiry into careers guidance for young people.
Junior minister Matthew Hancock is due to give evidence to the committee on Monday.