A plan has one person or, if a partner is added, two. Each person has their own pay, their own accounts and their own tax return; see taxes are per person. The household pools only the money left after tax.
Several rules depend on age: TFSA room, RRSP room, the FHSA, CPP, OAS and the length of the plan. The plan therefore needs a birth year for everyone in it.
When the age is not given
- No birth year. The person is taken to be 40 at the start of the plan.[1] That is close to the median age of the Canadian population (about 40.6 in 2025, Statistics Canada). It is a round mid-career age, chosen so that the first figures a visitor sees are neither a student's nor a senior's. It is not a legal fact: tax, CPP and registered-account rules read it until the real birth year is entered.
- The birthday. The plan asks for a birth year, never a date of birth, and takes every birthday as 1 January of that year.[2] Most rules need only the year. A few need the month: CPP contributions stop by the birthday month once a person is past 65, and CPP, OAS and a retirement start by it. A person born in December is treated as up to eleven months older than they are, so those dates can come up to eleven months early.
The plan lists these assumptions in the run's list of assumptions. A missing birth year is removed from the list as soon as one is entered; the January birthday stays, because there is nothing to enter.
How long the plan runs
A new plan runs through the year the younger person in it turns 90, until a length is chosen.[3] The choice of 90 and its limits are described in the plan horizon.
What it deliberately does not
- It does not guess a partner. A second person is in the plan only when one is added.
- It does not assume an age for retirement from the birth year alone; see retirement age.
- It does not model more than two adults.