In Leeds, a total of 1,317 families are yet to claim the 30 hours to which they are entitled.
The scheme was introduced in September of last year and working parents of three- and four-year-olds can claim if they earn more than 16 hours’ worth of minimum wage a week.
It has now been found from figures published by the Childcare Service that 5,280 codes were issued in Leeds by 8th January, but only 3,963 have been validated.
There was a website glitch in April which meant that many parents had problems accessing the scheme and some codes had to be issued manually.
Parents can only use the code for Ofsted-registered nurseries, playgroups or Sure Start Centres that have been signed up to the scheme.
In September, the shadow education minister Tracey Brabin said the scheme was “shrouded in mayhem.”
But the ex-education minister Robert Goodwill said that 71% of parents had found a childcare place and that the scheme had been “a great success story”.