Niall Collins (Limerick County, Fianna Fail) | Oireachtas source

On the six months versus nine months versus 18 months timeframe in terms of banding, business accounts and budgeting are done on an annual basis. It seems to me that 12 months is the norm in terms of the cycle of most businesses. There is not much difference between nine months and 12 months. Why was the nine months timeframe chosen given business norms are 12 months?