If the March fare increase is any indication, buying a three-month Puget Pass now (August-October) will allow you to dodge the October fare increase until November. Quoting from the previous post on the matter, crediting Seattlest:
According to the Metro rep we just got on the phone, you can either keep the old pass and pay an extra quarter each time you get on, or go down to the Second and Jackson office (201 S. Jackson) to pay the difference. (You’ll get a new pass.) Lucky holders of a three-month pass for the months January, February and March will not be liable for that extra quarter until their passes run out.
Metro can do whatever they want, so your mileage may vary. That was then, this was now, and they might not even approve the fare increase.
But I’m buying a three-month pass.