Higher earners who no longer wish to receive child benefit have until 7 January 2013 to apply to HMRC and opt out of receiving their benefit payments.
If your income is £60,000 or more and you or your partner are a recipient of child benefit it will be clawed back from you as tax charge under measures introduced on 7 January 2013. By opting out you might avoid having to repay your child benefit under Self Assemment.
If your income is between £50,000 and £60,000 you will face a claw back of 1% of benefit for every £100 of income.
The charge is worked out according to a fraction:
ANI - L % x Child benefit received
X
Where ANi is adjusted net income for the tax year
L is £50,000, and
X is £100
So, if your income is £55,000 and you receive Child Benefit of £1,752, you will find that your HICBC is £876 (50% of £1,752).
Always round down to the nearest whole number.
Therefore it may be unwise to opt out of receiving child benefit if your income is less than £60,000 as the tax charge will not exceed the benefit received.
See High Income Child Benefit Tax Charge