The rate of interest for the purposes of the Late Payment of Commercial Debts (Interest) Act 1998 shall be 8 per cent per annum over the official dealing rate in force on the 30th June (in respect of interest which starts to run between 1st July and 31st December) or the 31st December (in respect of interest which starts to run between 1st January and 30th June) immediately before the day on which statutory interest starts to run.