This depends on the duration you choose – for all three duration options, the maximum age you can be at the end of the duration is 85 years old (i.e. the maximum end date is the day before your 86th birthday). Therefore the maximum ages for the five durations are as follows:
5-year plan: 80 years old
10-year plan: 75 years old
15-year plan: 70 years old
20-year plan: 65 years old
25-year plan: 60 years old
Anyone who is 18 or older can start a savings plan, subject to the above maximum ages.