HMRC's Qualifying Care Relief for Foster Carers
HMRC know that foster caring plays an important role in the community - they know that foster carers are not the same as people who sell goods and services to others so, because of this, there's a special scheme for foster carers called 'qualifying care relief'.
You can find out all about it in this handy guide provided by HMRC: http://www.hmrc.gov.uk/courses/syob3/fc/HTML/fc_menu.html