Around one million letters will be issued during November to families affected by next year's child benefit changes.

The letters explain the new High Income Child Benefit Charge that takes effect from 7 January 2013.

The new charge kicks in when a taxpayer's or their partner's income is more than £50,000 in a tax year and if they, or their partner, receives child benefit.

For those with income of more than £60,000, the tax charge is 100% of the amount of child benefit. If income is between £50,000 and £60,000, the charge is gradually increased to 100% of the child benefit.

Those affected will need to decide whether to keep receiving child benefit and pay the tax charge through Self Assessment, or to stop receiving child benefit and not pay the new charge.

If their income is less than £60,000, the tax charge will always be less than the amount of child benefit, and they could lose money to which they are entitled if they stop receiving child benefit.

More details on the changes and what steps those affected should take, can be found at hmrc.gov.uk/childbenefitcharge/