Many British families are paying a far higher proportion of their income in tax than their counterparts in other advanced countries, according to a major new research study.
The study, believed to be the first of its kind, has been conducted for the charity Christian Action, Research and Education (CARE), which is campaigning for fairer tax treatment of families with children.
It charts the way over the past 40 years in the UK, the tax system has been increasingly tilted against one-earner married couples with children.
In 2006, a one-earner married couple with two children on average earnings of £30,800 a year paid 40 per cent more tax in the UK than in comparable countries belonging to the Organisation for Economic Cooperation and Development.
Compared with European Union states, one-earner married families are paying 25 per cent more tax.
The study also finds that the UK tax system disadvantages families in comparison with single people without children.
In other OECD countries, the tax paid by one-earner married couples on average wages is around 50 per cent of that paid by a single person on the same income.
In the UK, however, the figure is 75 per cent even when tax credits and child benefit are taken into account.
"Among highly developed economies, the UK is almost alone in operating a tax system that ignores spousal obligations," the report says.
Only Finland, Sweden and New Zealand have a system like the UK's. All other such OECD countries - including the US, France, Germany, Australia and Canada - take account of family circumstances.
