There is no claim to be made through this in the way your'e describing. All men and women, whether married or single, with our without children have the same tax code. There are exceptions such as having a company car etc. but being married/having kids no longer allows you a higher tax code. Curiosity is correct in saying that what used to be the additional allowance through taxation, is now claimed through Family Tax Credits. If your friend is not already claiming tax credits as well as Child Benefit, he needs to contact the Inland Revenue.