The research & development (R&D) firms Green Jellyfish and Kirby & Haslam were raided on 24 September under fraud allegations, but say they 'have nothing to hide'
Warrants were issued for several premises of the companies across the country on Tuesday 24 September.
HMRC have said the arrests have been made to ‘tackle suspected R&D fraud’ related to innovative science and technology projects.
A spokesperson from Green Jellyfish said: 'We understand that HMRC has a job to do, and we are fully cooperating and supporting them with the investigation, as we have nothing to hide.'
As well as the 11 arrests, more individuals have been asked to attend interviews under caution.
Jonathan Smith, HMRC’s Director responsible for Agent Compliance, said: ‘These arrests are just one small part of the comprehensive and wide-ranging action we’re taking to tackle suspected R&D fraud.
‘We’re committed to supporting honest businesses, and their agents, to get the tax reliefs they’re entitled to. We urge anyone with information about any type of tax fraud to report it to HMRC online.’
HMRC declined to comment further, saying: ‘We do not comment on identifiable taxpayers.’
A spokesperson from Kirby & Haslam said: 'We welcome the investigation from HMRC and understand they have to look into all claims made. We have been and will continue to be fully cooperative as we have nothing to hide.'
Until 26 September 2023 Green Jellyfish was known as Kirby & Haslam 1 on Companies House.