Search warrants were executed at two locations, and three men aged 28, 37 and 38 and 31 year old women were arrested at a business premises in Derby city centre.
A 31 year old woman was arrested after voluntarily attending a police station in Derby and a 35 year old man was arrested at a business address in Nottingham city centre.
All were arrested on suspicion of fraud. The searches and arrests are part of an ongoing criminal investigation into allegations of fraud relating to the automatic enrolment of staff into workplace pensions and underpaying workers.