In my experience, clients don't want to know all the legal details. They just want the answer.
That's why this is a walkthrough of our free BC child support calculator. If you came here for the number — what child support works out to in your situation — you can have it in about two minutes with three pieces of information. The rest of this post is for people who want to understand what's happening under the hood, and where the "mechanical" calculation stops being mechanical.
The short answer
Child support in British Columbia is set by the Federal Child Support Guidelines. The Guidelines apply whether you were married, in a common-law relationship, or never lived together at all. BC uses them for non-divorce cases through the Family Law Act, and they apply across the country for divorce cases under the Divorce Act.
Three inputs drive the calculation (assuming the payor lives in BC):
- The payor's gross annual income
- The number of children
- How parenting time is divided between households
Plug those into the calculator and you'll get a number. The tables themselves were most recently updated October 1, 2025, so the numbers reflect current federal figures.
Input 1: Payor's income
For a salaried employee with a straightforward T4, this one is easy. You take Line 15000 of the payor's most recent tax return — the "Total income" line — and that's your number.
For anyone else, this is where the real judgment lives. Some of the common situations where Line 15000 isn't the right answer:
Self-employment. If the payor runs a business or owns a corporation, the Guidelines allow adjustments for personal benefits run through the company, unreasonable deductions, and income retained inside a corporation. This is where most disputes about child support income originate.
Fluctuating income. Commissioned sales, bonus-heavy roles, seasonal work. Section 17 lets the court arrive at a fair and reasonable figure by looking at the last three years — sometimes by averaging, sometimes by using the most recent year, sometimes by discounting an outlier.
Under-employment. If a court concludes a payor is intentionally earning below their capacity, it can impute income — set a number based on what the person could reasonably be earning given their qualifications, skills, and work history.
Income over $150,000. The tables keep going above $150,000 — they give a base amount plus a percentage of income over each threshold. That table amount stays the default above $150,000. Section 4 gives a court discretion to depart from it, but only where the table amount would so exceed the children's reasonable needs that it amounts to a wealth transfer rather than support. That's a high bar, and the onus is on the party asking the court to deviate.
The calculator takes gross income as an input. Figuring out what that number should be is where most of the real work happens in a child support negotiation. If the payor's situation is anything other than a standard T4, don't take a calculator result at face value — the output is only as good as the income you put into it.
Input 2: Number of children
Usually straightforward: how many children are you calculating support for?
Two things worth flagging. Child support in BC typically continues until a child turns 19, and can continue beyond that where the child is still dependent — most commonly because of full-time post-secondary education or disability. And in some circumstances a step-parent can also have a support obligation under the Family Law Act, which is a separate question from the calculation itself.
Input 3: Living arrangement
Two scenarios the calculator handles:
Primary residence with one parent. The other parent pays the full table amount. Clean and simple.
Shared parenting (40% or more with each parent). Once parenting time hits the 40% threshold, section 9 of the Guidelines applies, and the calculation changes fundamentally. Instead of a single table lookup, the court has to consider three things together: each parent's table amount, the increased costs of running two households for the children, and the overall means and circumstances of both parents and the children. A straight set-off between the two table amounts is one possible result, but it isn't the starting point and it isn't presumed.
The 40% threshold matters because crossing it triggers this entirely different analysis. At 39% parenting time you're looking at the full table amount. At 40% or more you're in section 9 territory, where the number is more negotiable and more fact-specific — which is exactly why the characterization of parenting time is worth getting right.
Section 7 expenses
Beyond the table amount, the Guidelines require parents to share certain "special or extraordinary" expenses — the things that don't fit inside base monthly child support. The calculator handles these if you tell it the amount. Working out what qualifies is the judgment call.
The categories under section 7(1):
Childcare, but only where the recipient parent needs it because of employment, illness, disability, or education/training for employment. Routine after-school care that isn't tied to one of those reasons doesn't automatically qualify.
Medical and dental insurance premiums attributable to the children.
Out-of-pocket health expenses that exceed insurance reimbursement by more than $100 per year — orthodontics, therapy, prescriptions, and so on. The $100 threshold is net of insurance coverage, not gross.
Extraordinary educational expenses. Private school, tutoring, specialized programs. "Extraordinary" is a real test here; routine school supplies don't count.
Post-secondary costs.
Extraordinary extracurricular activities. The "extraordinary" language does work in that phrase too — not every hockey registration qualifies.
Once you have a total, the calculator splits it in proportion to income. If one parent earns 60% of the combined income, they pay 60% of the section 7 expenses, on top of whatever table amount is payable.
If you're unsure whether an expense qualifies, that's usually a question worth working through with a lawyer. Section 7 is also one of the most common sources of ongoing disputes between separated parents, which is why clear documentation of what's in and what's out is worth getting right at the agreement stage.
What the calculator doesn't do
The calculator gives you the section 3 table amount, the section 9 set-off where shared parenting applies, and the proportional split of any section 7 expenses you enter. A few things it deliberately doesn't cover:
Income imputation. If the payor's reported income isn't the right number, the right number has to be arrived at somewhere else — through negotiation, proper disclosure, or, in contested cases, a court application. The calculator takes whatever income you enter at face value.
Full section 9 analysis. In a shared parenting situation, the calculator shows you the straight set-off of the two table amounts. What section 9 actually asks a court to do is more involved than that, as noted above.
High-income discretion. For income over $150,000, the calculator shows you the table amount. Whether a court would order something different is a discretionary question with a high threshold.
From a number to an enforceable obligation
The calculator gives you an amount. It doesn't give you anything enforceable on its own.
For child support to be binding and enforceable — collectible through the BC Family Maintenance Agency and legally recognized if you ever need to vary it or enforce it — it has to live in either a court order or a written separation agreement that meets the requirements of the Family Law Act.
One thing worth understanding: child support is the right of the child, not the parents. An agreement can capture a number, but it can't foreclose a future application to vary if circumstances change materially. A well-drafted agreement doesn't try to — it sets the number fairly at the time of separation and builds in a clear mechanism for updating it when incomes change, a child moves households, a new child arrives, or post-secondary costs come into play.
Quick recap
- Three inputs: payor income, number of children, living arrangement
- The table amount is mechanical; the real work is in determining income correctly
- Section 7 expenses are on top of the table amount and shared in proportion to income — the calculator does the split, but you have to tell it what qualifies
- A calculator number is a starting point, not an enforceable obligation — and even an agreement can always be revisited if circumstances change
This guide is general information about how child support is calculated in British Columbia. It is not legal advice for your specific situation. Child support calculations can become complicated quickly — if your situation involves self-employment, disputed or fluctuating income, income over $150,000, or any meaningful complexity around parenting arrangements, talk to a BC family lawyer.