asked the Chancellor of the Exchequer what estimate he has made of the amount of tax lost to the Inland Revenue in 1973 by unlawful use of sub-contractors' exemption certificates.

The information on which to base such an estimate is not available, but £12¼ million was collected in 1972–73 by deduction at source, which is more than the total estimated evasion in 1969. Those who use certificates unlawfully lay themselves open to criminal prosecution.