Figures published by the Department for Education show that 195,345 out of 216,384 30 hours funded childcare eligibility codes issued so far have now been validated - equivalent to 90 per cent - leaving 21,039 codes that are yet to be validated.
Until parents' applications are verified by their local authority or childcare provider they cannot use the entitlement.
The figures represent an improvement on the 152,829 codes - 71 per cent - that had been approved at 5 September following the 31 August deadline for applications.
It is not clear why the codes are yet to be verified - reasons could include parents having yet to approach providers, problems with the verification system, local authorities and providers being slow at doing the verification, or a lack of available places.
Earlier in the year there were reports of parents struggling to register for the 30 hours scheme due to technical glitches.
Neil Leitch, chief executive of the Pre-school Learning Alliance, welcomed the increase in validated applications but said he remains concerned that more than 20,000 families are still unable to access 30 hours places.
"Given that childcare providers tend to have more spare places available during the autumn term, ensuring that all eligible children are able to access a 30 hours place is only going to get more difficult as the year progresses," he said.
"We know that, as a result of the continued lack of adequate funding, many childcare providers are still limiting the number of 30 hours places they are willing to offer.
"If the government is to have any chance of ensuring sufficient capacity as the policy continues to roll out, it must invest what is needed into the scheme."
The DfE said the number of applications verified will increase as the autumn term progresses because local authorities and childcare providers can continue to validate applications made by parents throughout the term.
The 30 hours free childcare entitlement is available to the children of working parents whose weekly pay is equivalent to at least 16 hours on the national minimum wage but less than £100,000 a year.