The agency scooped the business following a four-way shoot-out against Publicis Dialog, Partners Andrews Aldridge and Claydon Heeley. The pitch process was handled by COI.
The four-year contract will see Rapier take responsibility for producing traditional DM communications as well as some online and print executions to drive small businesses to the department's web-based information service, Business Link.
The website will provide employment information including details of equal opportunity rights, information on pensions, recruitment procedures, maternity leave and health and safety.
The campaign promotes the service as an alternative to creating a human resources department or consulting accountants and lawyers.