With just one week to go before the budget, a new report published on Wednesday by a Christian public policy has warned that UK families face a "crippling tax burden" in comparison to other developed nations.
CARE's 12th "Taxation of Families Report" compares the treatment of families in the UK with that of other developed countries. It suggests that one-earner families especially are facing a "triple whammy" which makes the UK "a cold place for families".
The latest figures show that at the Organisation for Economic Co-operation and Development (OECD) average wage, (£39,328 for the UK), the overall UK tax burden is 28 per cent greater than the OECD average both for single parents with two children and on one-earner married couples with two children.
The report revealed UK income tax also leaves UK families at a strong disadvantage in comparison to families from similar nations.
A one-earner married couple with two children in the UK will pay 39 per cent more than the equivalent French family, three times as much as the US family and more than 10 times as much as the German family.
At the OECD average wage, the UK income tax is 27 per cent greater than the OECD average for a one-earner married couple with two children.
The charity said the greatest concern is that "British aspiration is being chocked by absurdly high Effective Marginal Tax Rates" (EMTR).
CARE's research shows that for every additional pound earned, only 27 pence is kept. For those receiving housing benefit, the EMTR is 90.6 per cent. They keep less than 10 pence of the pound.
With the Chancellor making final preparations for the budget, CARE has called on the Government to conduct a full-scale review of the income tax system, with a focus on how it discriminates against those with family responsibilities.
The charity also wants an enhanced marriage tax allowance, as well as a range of other measures.
CARE's chief executive, Nola Leach, said the tax system is "crushing aspiration and social mobility".
"The fault does not lie in an individualised tax system, but rather in the fact our tax system is hyper-individualised, with little or no recognition of family responsibilities," she said.
"In a country that values aspiration and with a Government committed to social mobility, this cannot be right.
"For one-earner married couples with two children on the OECD average wage for the UK, the overall tax burden is suffocating.
"The income tax burden is hardly better especially when compared with France, Germany and the United States.
"To further add to the pressure modest income families are facing, the UK's eye-wateringly high effective marginal tax rates are crushing aspiration.
"If the Prime Minister is serious about levelling up across the country, he cannot ignore the way the tax system discriminates so obviously against those with family responsibilities."
Last month a group of more than 40 Conservative MPs called on Prime Minister Boris Johnson to put families at the heart of policy making.
In a letter to the Prime Minister, 44 Tory MPs called for a Ministry for Families to be created to promote the rights of single-earner families.