Plans for the full rollout of tax-free childcare in England have been delayed until March 2018 – five years after it was first announced.
It comes after parents grappled with technical difficulties on the official website, launched in April, they need to use to access the scheme.
In a written statement, ministers said they would be staggering applications by age of child between now and March.
All parents were supposed to be able to join the scheme by the end of 2017.
Under the scheme, the government will put in 20p for every 80p parents pay in childcare, up to the value of £2,000 a year.
The government opened its Childcare Choices website in April 2017.
Parents have had to use it to register for both the tax-free childcare scheme and another scheme offering free childcare to parents of three- and four-year-olds from September
Both were key planks of the government’s efforts to make childcare more affordable, with the tax-free childcare proposal announced by the then Childcare Minister, Liz Truss, in March 2013.
But the technical problems have meant some families have been unable to discover if they are eligible for the money-saving schemes.
A statement from Treasury spokesman Lord Bates said the government had “acted quickly” to address the problems, which reached a peak in the summer.
But he added that the service would now be “gradually” opened up to parents of older children, as his department continued to improve the system.
“This means we can manage the volume of applications going through the services, so parents continue to receive a better experience and prompt eligibility responses when they apply,” he said.
All eligible parents would be able to apply by the end of March next year, he added.
Neil Leitch, chief executive of the Pre-school Learning Alliance, said given the problems with the website, it was not surprising that the full rollout of the scheme was being delayed.
“That said, with many families still struggling with the cost of childcare, parents who had hoped to benefit from the scheme by the end of the year will be understandably disappointed by this delay,” he said.
Mr Leitch called on the government to invest “what is needed to deliver and maintain an IT system that both parents and childcare providers are able to use and rely on”.