Accounting firm WHK Horwath has expanded its market share in Western Australia, revealing plans to acquire Osborne Park firm Hayes Knight (WA) with effect from April.

The acquisition brings together Hayes Knight's four partners and 26 staff with WHK Horwath's 10 principals and 94 staff.

The combined firm, with 120 staff, will be the seventh largest in WA, according to WA Business News Book of Lists.

It will rank just ahead of PKF and Grant Thornton but will be susbstanially smaller than big four (Ernst & Young, PwC, KPMG and Deloitte), RSM Bird Cameron and BDO.

Hayes Knight WA, an independent franchise of the Australasian firm, was independently owned by its four principal partners, Alan Thomas, Paul Fazzari, Joe Grazziano and Mark De Luca.

The deal between WHK Horwath and Hayes Knight WA adds to a tumultuous last three years in WA's accounting industry with more than half a dozen mergers and name changes occurring since 2007.

The acquisition has major benefits for Hayes Knight (WA) clients and staff, chief executive Geoff Kidd said.

"The clients of Hayes Knight (WA) will gain access to a wider range of resources in key areas such as Specialist Tax Consulting, Audit and Corporate Finance. Hayes Knight staff will join WHK Horwath who are part of the public listed company, WHK Group. Being part of a larger group will provide staff with greater opportunities for career development and learning. It's a win-win situation."

"The addition of the well respected business advisory firm of 4 partners and over 20 staff will strengthen our service offering to the SME market" Mr Kidd said.

Mr Kidd said other than a name change - Hayes Knight (WA) will change their name to WHK Horwath - and access to a greater range of services, clients of Hayes Knight (WA) would not notice much difference.

"They will still deal with the same people and get the same high quality advice. We intend to maintain the satellite office in Osborne Park. There are no plans to merge into one office location," he said.

Mr Kidd added both firms had similar cultures and systems, which made the acquisition easier.

"Our vision is to maintain our growth strategy by acquiring quality firms which can compliment and build our service offering. The acquisition is in line with this vision. We see significant opportunities over the next five years to acquire quality accounting firms in the Perth Market," he said.

"Being part of a public listed company provides us with access to the capital required to fund this growth strategy."

The WHK Group is ranked the fifth largest accounting firm in the Australian market as shown in last year's BRW Top 100 accounting firms with revenue in excess of $350 million.

Mr Kidd said the WHK Group might be ranked number five in terms of size, but is focused on being the leading advisor to the SME market.