Here’s a .pdf copy of the Legal Practice Act, 1996 (Vic.) as at 5 April 2005 which I think is as at its repeal, but I’m not 100% sure about that.
Section 15 of the Legal Profession (Amendment) Regulations, 2007 inserted a new s. 3.4.3 into the Legal Profession Regulations, 2005 (Vic.). This is it, with my parenthesised interpolations:
‘3.4.3 Interest on unpaid legal costs
(1) This regulation is made for the purposes of section 3.4.21(4) of the [Legal Profession Act, 2004] and prescribes the rate of interest in excess of which a law practice may not charge interest under section 3.4.21 of the Act or under a costs agreement.
(2) The rate for the period commencing on and including the first commencement day and ending immediately before the second commencement day is the rate fixed under section 2 of the Penalty Interest Rates Act 1983 as at the relevant date.
(3) The rate for the period commencing on and including the second commencement day is the rate that is equal to the Cash Rate Target as at the relevant date, increased by 2 percentage points.
(4) In this regulation—
Cash Rate Target means the percentage (or maximum percentage) specified by the Reserve Bank of Australia as the Cash Rate Target;
first commencement day means the day on which regulation 15 of the Legal Profession (Amendment) Regulations 2007 comes into operation [r. 3(2) says reg 15 comes into force 6 months after the rest of the Regulations; r. 3(1) says the rest come into operation on the date they are made, which was 8 May 2007, so the first commencement day is 8 November 2007];
relevant date means the date the bill was issued by the law practice concerned;
second commencement day means the day that is 28 days after the first commencement day [6 December 2007].’