Shared custody: who pays what, and why money still moves
"We share custody, so we owe each other nothing." True for groceries, false for almost everything else. Here is where the line falls.
7 min read
One week at one house, one week at the other. On paper, shared custody settles the money question: each parent feeds, houses and clothes the child during their time, and nobody owes anybody anything.
Then the school meal bill arrives. Then the 180 € glasses. Then the school trip, the music lessons, the annual bus pass. None of those belong to a week or to a house, and that is exactly where the accounts start again.
Sharing time is not sharing costs
A 50/50 arrangement organises time, not money. It is the most common confusion, and the one that costs the most after two years.
What the alternation really settles: everyday costs during each parent's turn. Meals, rent, electricity, laundry, weekend outings. Whoever has the child pays, and asks for nothing.
What it does not settle:
- costs that are common to both houses: school meals, after-school care, activities, school transport, school insurance;
- exceptional costs: medical bills left unreimbursed, orthodontics, glasses, hearing aids, school trips, driving lessons, private schooling;
- purchases that travel with the child: the winter coat, the school bag, the phone. They stay in neither house, they move with them.
Shared custody does not automatically cancel maintenance
The idea that a 50/50 arrangement removes any maintenance payment is wrong in most legal systems. Where the law asks each parent to contribute in proportion to their means, that duty does not disappear because the nights are split evenly.
If one parent earns 1 800 € and the other 3 600 €, strict alternation means the child lives every other week with half the resources. A court can therefore order a contribution even under shared custody, to level that out. It is usually smaller than under sole residence, and it goes by another name in conversation: "the difference".
Two mistakes, in opposite directions:
- refusing any maintenance on the grounds that custody is shared. That is not a legal argument anywhere;
- believing that maintenance under shared custody covers exceptional costs. It does not, any more than it does elsewhere. The detail of that split, the prior-agreement rule and the sharing keys are covered in our article on splitting children's costs between separated parents.
Benefits and tax: two logics that do not match
This is the part almost nobody plans for, and it weighs more than a year of school meals.
Child benefits. Under shared residence, many systems allow them to be split between the two parents, on request. Without that request, they keep going to one parent alone, and the other sometimes finds out years later. The split is rarely automatic: it has to be asked for.
Tax relief. Where a child reduces a household's tax, shared residence usually means that relief is divided between the two parents rather than granted in full to one. Two halves are not worth one whole to the household that used to have it, and the gap runs into hundreds of euros a year.
What matters here for the day-to-day accounts: a benefit received by one parent alone is income that belongs in the balance. If one collects all the benefits and the bills are split down the middle, the split is no longer even, it is merely symmetrical.
Two homes, or why everything costs more
Two homes for one child means two beds, two desks, two sets of supplies, often two subscriptions. The total cost of shared custody is higher than that of a single home, and no sharing key makes that fact go away.
Hence a question worth settling early: what gets duplicated, and what travels?
| What happens | Who pays | |
|---|---|---|
| Duplicated | Bed, desk, spare clothes, toothbrush, a few toys | Each parent at home, no accounting |
| Travels | Coat, shoes, school bag, phone, laptop, instrument | Split: the purchase serves the child, not a house |
| Belongs to neither | School meals, care, activities, transport, trips, health | Split, on the written key |
The principle is easy to state and saves months of argument: you split what belongs to neither house. A bed bought for your own place is not shared. A coat that leaves on Sunday evening is.
Three sharing keys, and which one lasts
Whichever key you choose, write down the exact percentage. "We share the costs" is not a sharing key, it is the opening line of an argument.
- Half and half. Simple, readable, and fair when incomes are close. Unfair when they differ twofold: the parent earning 1 800 € pays the same as the one earning 3 600 €, so twice as much relative to what they have.
- In proportion to income. Add both net incomes, work out each share as a percentage, apply it to every bill. 2 000 € and 3 000 € give 40 % and 60 %.
- By category. One takes school meals and activities, the other health and clothing. Readable at first, but categories drift: one year of orthodontics wrecks the balance, and nobody recalculates.
Proportional splitting has a real drawback: it forces you to disclose your income, and to update it. A key set on 2022 incomes and never revisited quietly becomes wrong. Reviewing it once a year, in January, is enough.
What to record, every time
A shared cost that is not recorded the same day is a lost cost. Not out of bad faith, but because after three months nobody knows any more whether the 46 € museum trip was repaid or offset by something else.
Five pieces of information, and not one more:
- the date of the expense;
- who paid;
- the amount actually out of pocket, after any reimbursement from health insurance. This is the most common mistake: splitting the gross amount of a medical bill makes the other parent pay a second time for what has already been refunded;
- each parent's share, in currency and not as a percentage. A percentage has to be recalculated, an amount is simply read;
- the receipt, photographed there and then. January's orthodontics invoice cannot be found in June.
A threshold, so you are not counting snacks
Shared custody that counts everything becomes unliveable. Set a threshold once, and hold to it: below it, each parent pays without asking.
Twenty euros works for a lot of families. It lets through the snack, the cinema ticket and the birthday present for a friend, and it catches school meals, shoes and the doctor. The threshold is not there to be fair to the cent: it is there to keep the record bearable, and a bearable record is a record that actually gets kept.
Keeping this record without losing your Sundays
Three ways to do it, from least to most reliable.
In your head. Works for three weeks. After that each parent remembers very well what they advanced and much less well what the other paid, which is simply human.
A shared spreadsheet. Honest and free. A date column, a payer column, an out-of-pocket column, a column for each share. It holds up as long as one person fills it in, which is precisely the problem you were trying to avoid.
A cost-sharing app. Each parent records what they pay from their own phone, at the moment they pay, with a photo of the receipt. The balance works itself out and it is the same for both: there is no longer one version against the other.
That is what Kotisso does. One group for both parents, a percentage key that follows your incomes, the receipt photo attached to each expense, and a PDF statement to export when the accounts have to be shown to someone else. Balances, exports and receipts are free, with no limit.
The questions that keep coming up
Do we need a joint bank account? No, and it is often a bad idea after a separation: a joint account carries joint liability. Each parent pays their side, you record it, you settle by transfer once a month.
How often should we settle? Once a month. Often enough for the amounts to stay small, rare enough to avoid a transfer a week.
What if the other parent records nothing? Record what you advance anyway, with the receipts. A record kept by one person beats no record at all, and it becomes the basis for the conversation the day the question comes up.
What about a disagreement over a cost already incurred? Do not mix it in with the rest. Set it aside, keep recording everything else, and deal with it separately. One disputed expense blocking the whole statement costs six months of otherwise sound accounts.
Shared custody does not remove the accounts, it changes their nature: less maintenance, more split bills. What makes it liveable is not goodwill, it is having written down, once, the key, the threshold and the frequency, and then recording each cost on the day it lands.