Splitting children's costs after a separation: who pays what
Maintenance covers the everyday. Everything else is the one-off costs, and that is where it breaks down: no arrangement tells you what to do with a dentist's bill lying on the table.
6 min read
A pair of glasses at €180, a football camp at €220, the music school enrolment, the bus pass. Each of these is small. Together, over a year, they often add up to more than the maintenance payment itself. And unlike maintenance, nobody put a figure on them in advance.
That gap is what wears people down: two parents who agree on the principle end up arguing over the invoices, because the principle is written down and the invoices are not.
Three layers, and the line between them
Almost every dispute comes from mixing up three different things.
| What it is | Who pays | |
|---|---|---|
| Maintenance | A fixed, usually monthly amount, set by a court or by agreement | The paying parent, every month |
| Everyday costs | Food, ordinary clothes, ordinary activities, school supplies | Covered by maintenance, or by each parent during their own time |
| One-off costs | What falls outside the ordinary and was not foreseeable: unreimbursed healthcare, private schooling, school trips, braces, an instrument | Split by an agreed key, usually equally or in proportion to income |
The classic trap is treating an ordinary cost as a one-off. A pair of trainers, however expensive, is still clothing. School meals, on the other hand, are regular and predictable: they belong either inside maintenance or in a separate split, and if your arrangement does not name them, they will come up every single term.
Agree before you spend, in writing
This is the single most valuable habit in the whole article, and the one that costs the most when it is missing.
A parent who commits to a large expense alone, without the other's agreement, may well end up paying for it alone.
In most legal systems, an expense incurred unilaterally is hard to recover, and the reasoning is the same everywhere: the other parent never had the chance to say no, or to suggest something cheaper. The universally accepted exception is medical urgency, where you treat first and discuss afterwards.
It cuts both ways, and that is exactly what makes it a protection rather than a constraint: nobody wakes up to a bill somebody else decided on.
In practice, agreement has to be written and dated. A text message is enough. A verbal yes given in a school playground no longer exists six months later, when the invoice lands and each memory has quietly done its work.
Choosing the key: three that work
Equal shares. Simple, readable, no arithmetic. It is the most common arrangement and it fits perfectly when incomes are close. Its weakness is mechanical: with very unequal incomes, it weighs about twice as heavily on the lower earner.
In proportion to income. Add both net incomes, work out each share, apply it to every invoice. A parent on €2,000 and a parent on €3,000 split 40 / 60. This is the key most family courts lean towards, because it tracks capacity to pay rather than a headcount.
One cost each. Some parents avoid all arithmetic by taking whole categories: one takes school meals and activities, the other healthcare and clothing. It works while the amounts stay close, and it derails the year €2,000 of orthodontics lands on one side. If you go this way, check the balance once a year with the figures in front of you.
Whichever key you pick, write it down with the exact percentage. "One-off costs will be shared" is not a splitting key, it is the opening line of a disagreement.
What to record, every time
A shared invoice that is not recorded the same day is an invoice you will find again in a year, with no idea whether it was ever repaid. Five points:
- the date of the expense, not the date you remembered it;
- the amount actually left to pay, after any health insurance or state reimbursement. That is the figure that gets split, never the sticker price;
- proof of prior agreement: the text, the email, the clause;
- the receipt: photograph it immediately, thermal paper fades within months;
- who fronted the money, and what is still owed afterwards.
Settling up: ask early, ask small
Two mistakes repeat themselves.
Waiting. A parent who lets six months go by so as not to make a fuss ends up asking for €900 in one go. The amount has not changed; what has changed is that it has become unpayable in one instalment, and therefore contentious. A request sent within the month almost always gets paid.
Netting off in your head. "They owe me €200 but I had the children an extra week, so we're even." These mental adjustments are never shared: each parent keeps their own version, and the two versions never match. Record the expense, record the repayment, and read the balance instead of guessing it.
If the conversation has broken down, most countries offer family mediation before anything adversarial, often with a free first session, and it resolves far more of these than a court ever sees.
Keeping the tally without losing your Sundays
A spreadsheet works, as long as both parents open it, both keep it up to date, and it is backed up. In practice one person keeps it and the other discovers it at the end of the year: that is no longer a shared tally, it is an invoice.
That is exactly the problem Kotisso solves. Create a group with two people, record the expense when it happens, set the key once, and both of you see the same balance, live, on your phone.
Three things matter particularly in this situation:
- splitting by percentage, which applies your key to every expense without recalculating it. 40 / 60 is entered once;
- the photo of the receipt, attached to the expense. The orthodontist's invoice is not something you hunt for, it is on the line;
- the statement exported as a PDF or spreadsheet, dated and backed by the figures. That is the document to attach to a request, take to mediation, or simply send once a year to close the year off.
None of that costs anything: the tally, the receipts and the export are all in the free version.
Questions that keep coming up
Are school meals a one-off cost? Almost never, because they are regular and predictable. They usually sit inside maintenance, or in a separate line if your arrangement says so. The real advice: name them explicitly, one way or the other.
What if the other parent refuses to pay their share? Send a written statement first, with the receipts and the key. If nothing happens, a formal letter, then family mediation. Enforcement generally exists only for maintenance set by a court, not for a reimbursement between parents with nothing in writing, which is precisely why the splitting clause needs to be precise.
Can the key be changed? Yes, by agreement between the parents, or by going back to court if incomes have changed significantly. A key set on incomes from five years ago represents nothing.
Should everything be split, even €12? No, and it is better not to. Set a threshold: below it, whoever pays, pays. Above it, you ask and you split. A threshold at €50 or €100 stops the relationship turning into bookkeeping.