Just so that I know where to find it next time that I need to settle a “discussion”; a cheque becomes stale fifteen (15) months after it is drawn. A stale cheque may be rejected by a bank – the cheque can be considered expired. In practice though banks are now likely to treat a cheque older than 6 months as being stale, which is the normal treatment in the rest of the cheque-writing world.
Sources: ANZ [^], Australasian Legal Information Institute [^].