A growing trend of firms having non-equity partners was also helping drive profitability, Mr Bassett told NZ Lawyer.
"Over the last few years we have seen, from our work with legal firms and reinforced by this survey, that the lock step partnership formula is still a popular choice not only for succession planning but also expanding the business."
Mr Bassett said the location of profitable firms was intriguing.
"I think the interesting thing was that the city firms have been doing better than the suburban firms, and that really surprised me.
"Thinking it through, I think it is probably because during the recession, the suburban firms had that lower overheads are that were able to get their house in order -- they weathered the storm better than some of the central city firms.
"Obviously, now the city firms have bounced back -- particularly the boutique litigation firms that have their structure right."
Common characteristics shared by profitable law firms:
•Average gross fees per equity partner in excess of $1.2m
•Partner charge out rates of $400 plus
•Staff salaries to gross fees generally 30 to 35 per cent
•Partnership of two or more equity partners with at least one non-equity partner
•Overheads (excluding interest and salaries) to gross fees of 25 per cent or less
Source: Moore Stephens Markhams director Sam Bassett