Thousands of families will miss out on up to €12 a week, possibly for months over problems with the government's new childcare subsidy scheme.

While every family with children under the age of three will get the universal payment from September, some 9,000 who would be entitled to an extra subsidy will miss out.

The government is blaming a delay with a new IT system and the fact it won't have passed legislation for revenue to share data with the department of children.

Children's minister Katherine Zappone says families at the higher end of the lower income group will lose out until they fix this: