A poll of 1,394 nurseries, pre-schools and childminders by the Pre-School Learning Alliance found that 52 per cent intend to increase or introduce fees for goods and services including food, trips and nappies.
Meanwhile, 49 per cent said they intend to charge parents more for non-funded childcare places to claw back losses from the 30 hours offer, which comes into effect tomorrow (1 September).
A total of 74 per cent of the providers who took part in the online survey said the money the government is providing to cover the cost of the free places is less than the cost of providing those places. On average, the providers reported a shortfall of 18 per cent between the funding of the policy and their costs.
Eve Wort, the former principal of Anchors Nursery School in Hampshire, said the funding gap prompted her setting to close at the end of the summer term. "Our funding was reduced from £4.44 per hour to £4.36 per hour, when our hourly costs are around £6 per hour," she said.
The survey also found that 38 per cent of providers do not think their business will be sustainable in a year's time.
Neil Leitch, chief executive of the Pre-school Learning Alliance, said the 30 hours policy is "in chaos".
"Parents who expected 30 hours of free childcare to take up when and how they wanted are now facing additional fees and charges and either unexpected restrictions on when they can take up their places or a struggle to find places altogether," he said.
Leitch added the Department for Education has mismanaged the policy and must act to rectify the situation.
"Every week we're hearing of more and more parents struggling to find places that actually suit their childcare needs," he said.
"Every week we're hearing of more and more childcare providers being forced to shut down as a result of the 30 hours.
"This simply cannot continue. It's time for the government to step up, admit it got this wrong and fix the mess that it has made. Otherwise it will be parents and providers who pay the price."
Sarah Presswood, manager of George Perkins Day Nursery in Birmingham, said her nursery felt it had no choice but to offer places under the 30 hours policy despite the funding gap.
"We are offering 30-hour funded places because we're concerned that if we don't families might look elsewhere for childcare," she said.
"However, the only way we can do this is to ask parents to pay for additional services, which are things we have never charged for before. Additionally, we have put fees up for younger children and non-funded hours."
Despite the worries highlighted by the survey, most providers (58 per cent) said they felt confident that the number of 30 hours places they planned to offer would meet demand.
The Department for Education said the 30 hours offer would save the families of three- and four-year-olds thousands of pounds a year.
"High-quality childcare not only helps our children get the best start in life, it supports many parents who want or need to work," Education Secretary Justine Greening said.
"For too long lots of families really struggled to manage the cost of childcare and that's why we have delivered on our promise to provide 30 hours free - saving working families around £5,000 a year."
The 30 hours policy has faced several problems in recent months, including technical problems with the Childcare Services website that left thousands of parents unable to sign up for the childcare on offer.