Child and Working Tax Credits were introduced in April 2003.
Estimates of the numbers of families with tax credits awards, by constituency and local authority, based on final family circumstances and incomes, are available in the HMRC publication "Child and Working Tax Credits. Finalised Awards. Geographical Analysis" for the years 2003-04, 2004-05 and 2005-06. These publications are available on the HMRC website at:
HMRC do not produce statistics separately for child tax credit and working tax credit.