A tax cut that will give the richest people almost £100,000 a year could have increased child benefit for more than 12 million children, according to a trade union study.
Unison said the Government's decision to cut the 50p rate of tax would hand thousands of millionaires an average of £97,800 next year.
The union estimated that if this tax had been collected, it could have funded an increase to child benefit for the first two children in every family - effectively helping over 12 million children in nearly eight million families.
The freeze on child benefit will mean that a family with one child will get £114.50 a year less than they would have received if child benefit had been raised in line with CPI, while a family with three children will be £265.66 a year worse off, said Unison.
The study comes as the Daycare Trust and Family and Parenting Institute found just one in five local authorities have enough childcare for parents with children under two, and one in three for school age children.
General secretary Dave Prentis said: "Once again, this government's claim that we are all in this together has been exposed as a sham, and they've chosen to line the pockets of millionaires while children across the UK suffer in poverty.
"The Government faces a stark choice on Budget day - feather the nests of rich individuals or help families who are struggling in the recession."