Some parents also reported that they were asked to pay fees upfront and were then reimbursed for the cost of the free entitlement at a later date.
Many parents were uncertain about how the free entitlement was calculated.
Just half of parents who receive a bill from their childcare provider were given a breakdown of costs, clearly showing what hours were free and what they had to pay for.
However, other parents reported that they were billed clearly and that the system worked well.
Just under a quarter of parents (23 per cent) said they had been asked to pay for some of the free entitlement – for example, when a session was longer than the 2.5 hours under the previous Code of Practice.
More than half of the parents surveyed (52 per cent) had been asked to pay for extras, such as meals and outings.
Under the new Code, providers may charge for additional services, but nurseries must give parents the option to send their child to nursery with a packed lunch.
The survey also revealed that providers referred to the free entitlement in various ways but that the most common terms used were nursery grant or a free place.
More than 500 parents took part in the research, which was carried out with Netmums, to coincide with the extension of the free entitlement to 15 hours a week and the introduction of the new Code of Practice.
The Daycare Trust said many providers struggle to cover the cost of the free entitlement.
Chief executive Alison Garnham said, 'It is of great concern that there is so much uncertainty and confusion among parents. We know from the high take-up rate of the free entitlement that parents really value formal childcare. However, when parents are asked to pay upfront costs or top-up fees, it is the poorest families, whose children stand to benefit the most from the free entitlement, who are most likely to be deterred from taking it up.'
