The raids were part of an investigation into suspected tax fraud and money laundering believed to total approximately £35m.
HMRC officers seized computers and business records from three private and 12 business addresses in Bath, Bournemouth, Bristol, Berkshire, Exeter, Stroud, Swindon and Yate.
“Tax fraud is often thought to be victimless, but it isn’t; the public lose out on vital funds for essential services,” Colin Spinks, assistant director of the HMRC fraud investigation service said.
The seven men and three women arrested were interviewed and released under investigation by the HMRC.
The investigations are continuing.