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Child support and shared kids' expenses, tracked properly

Updated October 7, 2026 · 6 min read

Between co-parents, two kinds of money move at once, and they follow different rules: the support one parent owes the other every month, and the child's costs that both share. Mix them up and the numbers are wrong. Keeping them apart takes a method.

The short answer

The math, worked out

Thomas owes Claire $500 a month in support. In October he also paid $200 for school lunches, a cost both parents share equally.

Thomas transfers $400 and October is settled. Without this math, two classic mistakes: sending $500 and forgetting to claim the $100 back, or sending $300 by deducting the whole lunch bill — when half of it was his to carry anyway.

Why support is not a shared expense

This is the most common mistake, and the most expensive. A shared expense is a purchase several people benefit from: you divide it. Support is not that. It does not buy anything in particular — it settles a recognized imbalance between two households.

Enter it as a $500 expense shared between two parents and the app puts $250 on each. The paying parent now appears to owe $250 instead of $500. The gap widens every month, and nothing flags it.

The rule is simple: record support as a debt from one parent to the other, never as a purchase to divide.

When the split is not fifty-fifty

Children's costs are often shared in proportion to income rather than down the middle. A 60/40 split is entered as shares: 6 against 4. A $200 lunch bill then becomes $120 for one parent and $80 for the other.

It adds up: across a year of lunches, activities and supplies, the difference between 50/50 and 60/40 runs into the hundreds.

Allowance, and the child who is not in the group

One parent hands the child a $50 allowance, and the amount should be shared. Should the child be added to the group? No. The members of a group are the people the money is split between, not the people it is spent on.

So the allowance is recorded as a $50 expense, paid by the parent who handed it over, split between the two parents. The child appears nowhere, and the math is right.

What WeSplit does with this

The "Child support" group type takes the monthly amount and who pays it. Support is then added on its own every month, and the balance shows directly what is left to pay given the costs already fronted. The amount can be changed when support is revised; it can be stopped and resumed.

The group arrives with the categories that matter: school, lunches and childcare, health, clothes, activities, allowance.

Keeping track without losing your evenings

The method is worth nothing if nobody keeps it up. Between separated parents, tracking usually fails the same way: each keeps their own receipts, and six months later a year of school lunches has to be rebuilt from memory.

One list, kept by both. Two parallel sets of accounts produce two truths. Tracking starts with both parents writing in the same place, and seeing the same thing.

Record it when you pay. Thirty seconds at the till beats an evening of reconstruction. It is the only habit that really matters; everything else follows from it.

Keep track of who paid, not just the amount. “84 of school lunches” says nothing; “84 of school lunches, paid by Clara on 3 October” can be checked.

Settle on a fixed date. Once a month, look at the balance, transfer the difference, start again from zero. An account that never gets settled becomes a source of conflict in itself, because the sum eventually grows too big to pay in one go.

Two cases come up often enough to have their own page: costs split in proportion to income, and holidays where the stays are unequal.

What this does not replace