March’s agreement will create a new company with more than 30 staff members and a doubled client portfolio.
Former BDO directors Michael Crowe and Martin Kneale will sit alongside Grant Thornton directors Dennis McGurgan and Richard Ratcliffe at the top of the new venture, which will continue to run under the Grant Thornton title.
Crowe said: “We are delighted to be joining Grant Thornton to enable continuity of service to our clients and to provide job security for our employees.”
McGurgan said: “I hope our confidence in the ongoing growth of the island’s economy is reflected in the substantial investment and significant development this merger represents.”
BDO employees will move into the Grant Thornton offices in Douglas for the venture and will retain their original roles.
Last April, BDO completed its merger with PKF.
BDO has 24 office locations in the UK, more than 3,500 employees and generates revenues approaching £40m, according to a statement released by the company.
Grant Thornton, a member of Grant Thornton International, provides accounts preparation, auditing, tax compliance and tax advice to a variety of clients. It also advises on the setting up and administration of offshore tax planning, estate planning and confidentiality.