"We have been impressed at Hood Sweeney's reputation on both a local and national scale and welcome it as a new aligned partner in our national network," Countplus executive chairman Barry Lambert said in a statement to the Australian Securities Exchange.
Consideration for the investment is a cash payment of $3.75 million with further performance-based payments over two years.
Settlement is expected to be completed before the end of October 2012, the statement said.
The transaction is expected to be immediately earnings per share accretive.
The purchase represents the first made under Countplus' new progressive acquisition model, in which an initial minority interest is taken, the company said.
The model allows principals to retain a direct interest and could easily facilitate the entry of new principals into an equity position while reducing the acquisition risk for Countplus - which was established as a subsidiary business of Count Financial Limited in 2007.
Hood Sweeney provides accounting, financial procurement, wealth management and information technology advice to individuals and small to medium-sized businesses (SMEs) through its three offices in Adelaide, Whyalla and Kadina.
It has 86 staff and last financial year reported revenues in excess of $16 million.
The acquisition will position Hood Sweeney to offer support in South Australia's ageing population - which is looking at ways to maximise their superannuation investment - plus a growing number of people in SMEs that require trusted advice, Mr Lambert said.
"For SMEs in particular, Hood Sweeney has successfully developed a unique model of integrating its client services to encompass accounting and business advisory, financial planning, finance and technology services.
"This level of integration is a key differentiator from traditional accounting firms."
Under the agreement, Hood Sweeney will continue to operate independently under its own Australian Financial Services Licence and Australian Credit Licence.
Countplus will not have any representation on the Hood Sweeney board.
