Parents and providers are left in confusion by the troubled introduction of 30 hours of free nursery to three and four-year-olds

Tens of thousands of parents are still waiting to find out if they can take up a government offer of 30 hours’ free childcare days before the scheme is due to be launched.

According to the latest figures, revealed in a letter sent by the Department for Education to local authorities and seen by the Observer, 82,000 parents entitled to the extra childcare have not yet secured a place for their three and four-year-olds. The offer, which doubles the current government-funded allowance, was a flagship Tory election pledge and is due to be implemented on Friday. But the policy appears to be mired in confusion amid claims of a funding shortfall and technical hitches.

According to new research given to the Observer by the early years shadow minister Tracy Brabin, three-quarters of childcare providers expect the policy to have a negative impact on their business and fewer than 7% say it will be positive. The same research claims that the scheme is underfunded, and that as many as one in three nurseries have not yet decided to offer any free places.

“I’m deeply concerned that many children won’t have access to the quality childcare they deserve – and that parents were promised,” said Brabin, who received 660 responses after she set up an online survey of childcare providers over the summer.

The Pre-School Learning Alliance estimates there is a 20% shortfall between the amount the government is giving local authorities to fund the scheme and the actual cost to nurseries. It said that some nurseries will have to close as a result, and some have already gone under.

Eve Wort has recently shut down her village nursery in Hampshire after running it for more than 20 years. She said she could not afford to take part in the scheme and knew she would lose children as a result. “I knew parents would have an expectation in September that they could get 30 hours for free, and there might be a stampede, in the short term, to nurseries which joined the scheme. Then I might have been left without enough money to pay my staff redundancies. I can’t bear it. I feel absolutely devastated.”

To add to parents and providers issues, the HMRC-operated childcare website is causing huge headaches. Parents need to apply for a code proving they are eligible before Wednesday or they will have to wait until January.

Facebook Twitter Pinterest Tracy Brabin, the early years shadow minister, fears that many children will miss out because the scheme is being underfunded by the government. Photograph: David Sillitoe/The Guardian

In a letter to the chairwoman of the Treasury committee, Nicky Morgan, published on Wednesday, HMRC revealed that one in 20 parents who have used the service since April have suffered at least one technical problem during their application, and 45% of callers to the helpline have needed to call more than once.

The codes have also been supplied for two and five-year-olds, neither of whom qualify, while some parents in receipt of housing benefit and childcare and working tax credits have pulled out of places, unsure if they will be better or worse off.

A Department for Education spokesman said: “We are determined to support as many families as possible with access to high-quality, affordable childcare, which is why we are investing a record £6bn every year by 2020 and doubling the free childcare available to working parents, saving them up to £5,000 a year per child.

“This funding includes an additional £1bn a year by 2019-20 to pay for the free offers and to raise the national hourly rate to local authorities for three and four-year-olds to £4.94.”

HMRC said anyone in receipt of tax credits who is concerned about the scheme should check its online childcare calculator. A spokesman said: “Parents who apply in time and who get their code after 31 August will still be able to use it. Nobody need lose out as a result of the technical issues.” He added that parents can seek compensation if they suffer unreasonable delays.