International Financial Group (IFGL) has completed the deal to buy Sovereign Pension Services (UK) from the Sovereign Group.
Work will now begin to rebrand the international SIPP and SSAS administrator and operator as IFGL Pensions by the middle of 2023, IFGL said in a statement on 1 March.
IFGL announced its intention to buy the company in August this year and the deal has been going through the regulatory approval process since.
It will continue to be based in Bromborough, Wirral, where it employs 45 staff.
IFGL chief executive David Kneeshaw said: "We are delighted we can now officially welcome SPS into the IFGL family. We have ambitious plans for their future - as I said when we announced the deal last year, this is a strategic acquisition which will allow IFGL to provide a wider range of services and value to customers and advisers.
"There is a gap in the market for a service-led and cost effective SIPP proposition and SPS, soon to be IFGL Pensions, will ably fill that gap."
Sovereign Group chief executive Gerry Kelly said: "Our work with IFGL since the deal was announced in August 2022 has confirmed that we made the right choice to take the business forward and we wish IFGL and the dedicated staff of SPS every success in the next stage of their development."
IFGL also owns RL360, Friends Provident International Limited and Ardan International. It provides investment, savings and protection solutions to international investors around the world.
Upon completion of this deal, IFGL had 216,000 customers, $23bn assets under administration and 570 staff.