This is the final phase of the scheme, which has been gradually rolled out since April 2017.

Under the scheme, for every £8 parents pay into their childcare account, the government will add an extra £2, up to £2,000 per child per year. The money can go towards a range of regulated childcare options, including nurseries, childminders, after-school clubs and holiday clubs.

Parents, including the self-employed, can apply online by visiting Childcare Choices. The site has had teething problems with reports of parents not receiving benefits on time but the government said these are being resolved.

Elizabeth Truss, chief secretary to the Treasury, said: “More parents will be able to work if they want to and this demonstrates our commitment to helping families with the cost of living.

“All eligible parents with children under 12 can now apply through Childcare Choices and should take advantage of the available support.”

More than 340,000 families have successfully applied for the service. Of these, more than 190,000 have a Tax-Free Childcare account.

A recent OECD survey found that the UK had the highest childcare costs of any developed country. It looked at the cost to send two children (aged two and three) to a typical childcare centre (or nursery) for at least 40 hours each week.

It assumes both parents are working, where one parent earns an average wage and the second parent earns 67% of average earnings and took into account government help.

The UK was 15% ahead of its nearest rival (New Zealand) with childcare costs taking 55% of average earnings. However, in analysing the survey, the BBC pointed out that parents on lower incomes would be eligible for additional support, which would reduce childcare costs.