Letters will be arriving at 100,000 Westcountry households from today warning families that they may lose their child benefit.
Under a controversial decision, families will start losing money on a sliding scale if one parent earns more than £50,000.
The handout will be axed completely if a parent brings home more than £60,000 a year – a family with three children could be worse off by about £2,450 a year.
However, if both parents earn £49,000, the child benefit payments will not be touched, an anomaly that has angered some Tory MPs, despite the scheme's introduction under the current Government.
The Office for National Statistics says 7,884,780 families in the UK received child benefit in August last year – up from 7,248,336 in 2003 – and they had a total of 13,721,180 children. There were 621,605 families in the South West, a rise from 570,735 in 2003.
Just under 265,000 of the families in the region have one child, 244,000 have two, over 70,000 have three, just under 16,995 have four youngsters and 5,310 have five or more.
Child benefit is £20.30 for the first child and £13.40 for each sibling, and the Tories say around 15% of total recipients will lose out, which would be more than 93,000 in the South West.
Deputy Prime Minister Nick Clegg admitted yesterday that it was an "excruciatingly difficult" decision.
A Downing Street spokesman said: "It's very difficult to justify continuing to pay child benefit to the wealthiest 15% of families."
The changes take effect in January.