For any additional children, the rate is reduced, but could still make a big difference to the income of millions of British families.

The weekly rate for additional children is £14, or £728 for a full year of the benefit.

That means a family with two children could lose £1,827.80 each year by not having access to Child Benefit.

Ms Williams said: “The combination of rising inflation and the freezing of allowances means that more people fall into the higher rate tax bands as time moves on.

“This is a tax rise by the back door and will ultimately result in a greater tax take for the Chancellor – a concept known as fiscal drag.

“It’s a way of raising more tax without raising tax rates. Tax by stealth!”