Childcare providers fear the government’s new 30 hours free care scheme is in jeopardy due to technical problems being faced by parents registering online.
More than 2,000 people are registering for the offer every day. However thousands more have reported struggling to access the system online.
A telephone helpline has also suffered technical difficulties.
Parents have been complaining of glitches in the system since it launched in May.
From September some working parents will qualify for 30 hours of free childcare a month, doubling the existing offering of 15 hours.
However parents have to lodge their application for the scheme online in order to obtain a code to show their childcare provider and unlock the funding.
An HMRC spokesman said: “We know that some parents and childcare providers have experienced difficulties accessing the service, and we are sorry about the inconvenience.
“We’ve now made significant improvements based on customer feedback, and on average more than 2,000 parents are applying successfully every single day.
“We continue to make updates to improve the customer experience and ensure everyone can easily access their account.
“Parents and providers experiencing difficulties or needing technical support can phone the childcare service helpline on 0300 123 4097.”
The Pre-School Learning Alliance said the scheme could only succeed if the problems were solved.
Chief executive Neil Leitch said: “The government has claimed that working families could benefit from thousands of pounds of savings as a result of the tax-free childcare and the 30-hour offers, but of course, for that to happen, the IT system underpinning both schemes has to actually work.
“Indeed, the recent 30-hour pilot evaluation report explicitly stated that the effective implementation of the childcare service system was vital for the policy to have any chance of succeeding.”
National Day Nurseries Association chief executive Purnima Tanuku said: “With the rollout of the government’s 30 hour funded childcare places from 1 September, some parents are getting worried that they won’t even be able to access their places in time because they are being let down by the IT system.
“HMRC must ensure they resolve problems with the website as a matter of urgency and reassure parents and providers.”
To register for free childcare and for information visit the HMRC website.