Money Marketing reported that Hallett had left Pointon York after 12 years with the firm in March.
Hallett says her new firm will provide independent pension products and services and will focus on delivering competitive solutions for advisers and clients.
Based in Milton Keynes, the firm will operate independently of any investment houses.
Hallett says: “Our account management approach for administration, technical support for advisers and their clients and access to online information from day one, will make the whole adviser/client experience much more meaningful.
“Taking away communication barriers is key to building successful relationships between all stakeholders and creates strong foundations for a solid and sustainable relationship.”
Carey Group will also provide QROPS, international pension scheme, share option and employee benefits administration services through its Guernsey office.